Just One Fish

The Problems of Aquarium Release 

A lot of people buy fish that grow too large for their aquariums. Most times it isn’t their fault as pet stores often don’t inform people how large their goldfish, oscar, or pleco will grow. A couple of years down the road, these massive fish can cause problems for unsuspecting aquarists. Some stores will take back overgrown fish and try to re-home them, but this is costly for the store.

Oscar in a 20 gal (Oscarfish.com)

Many times these large pets are just released into local lakes and rivers because people assume just one fish won’t cause any harm. This leads to things like a pacu being caught in North Carolina and Utah. This is by no means good, but it isn’t the end of the world as most of these fish die when winter comes. But what happens when you get a cold-tolerant species like goldfish? Or when the winters just aren’t cold enough to kill off tropical fish like in southern Texas and Florida? If enough fish are released you can, and do, get breeding populations of these fish.

This causes major problems for the local ecosystems. In the case of oscars (Astronotus ocellatus) suddenly local fish have to deal with a whole new predator. Those small fish are what feed the gamefish like bass and perch. The large predators of the lake suddenly have to deal with competition, something they might not have dealt with before. A lot of times, the new fish is a stronger competitor and drives the native fish towards extinction.

In the case of goldfish (Carassius auratus auratus), they don’t directly compete with the native fish; it’s the feeding action of these fish that cause trouble. In the wild, goldfish quickly lose their gold coloring and look more like regular carp. Just like carp, they root around in the substrate. This causes the water to become cloudy, impeding the growth of plants in the substrate. These plants offer a refuge for juvenile native fishes; without them the juveniles become prey for larger fishes. The increased turbidity can also be a problem for fishes that feed on benthic insects as the insects rely on a layer of algae that cannot form when the water is cloudy. So far two species have suffered negative effects on wild populations since goldfish were introduced into their habitats: the Sacramento sucker Catostomus occidentalis (Moyle 1976) and Pahrump poolfish Empetrichthys latos latos (Deacon et al. 1964; Lee et al. 1980 et seq.) There may be many more that haven’t been studied yet.

Researcher holds up a giant goldfish pulled from Lake Tahoe
where they have been causing unrest in the local ecosystem.
(kcra.com)

Not only are released aquarium fish a problem with the native fish, but they can be problematic for humans, too. Loricariid catfish, commonly called plecos, can’t survive the winters in the  northern US, but they can and do thrive in the southernmost states. Florida, Texas, Louisiana, and Nevada all report breeding populations of these fish. These large catfish breed in burrows, which becomes a problem when they are found in high numbers. These burrows lead to increased erosion (Nico 2009). This can be very problematic when they burrow into levees as this causes the levees to erode from within. The damage may not be noticed until after the levee has breached. 

It’s not just freshwater fish that present a problem. Saltwater fish released into non-native habitats can also cause problems. The most notable is the lionfish (Pterois volitans). These are beautiful fish that outgrow most normal sized home aquariums and when released into the ocean survive and thrive. They have been reported as far north as Massachusetts and breeding populations are established from North Carolina to Florida, Bermuda, and all around the Caribbean. Lionfish are predatory and have a voracious appetite. They prey on important local fishes such as those that keep reefs clear of algae and juvenile foodfish that are economically important like grouper and grunts. Lionfish have no predators in the Caribbean ecosystem and are covered in large, venomous spines. These spines deter anything from eating them and cause harm to divers that approach them. Luckily there is something divers and fisheries managers can do about these fish: harvest them. They are targeted by spearfishing operations which appear to be having an impact on the population.

It’s not just fish released from aquariums that can cause trouble; plants have also been known to make it into local waterways when aquarists toss them as well.. Some of the most notable examples of this come from floating plants like water hyacinth, hygrophila, water lettuce, and giant salvinia. These plants are rapid-growing and will choke out waterways making boat travel very difficult. Controlling them requires intensive management.

These are some of the worst cases of the consequences of aquarium release. I don’t want this to turn you against the aquarium hobby—I want these examples to open your eyes to what happens beyond your fish tanks. These examples are sad, and we can’t do anything to stop what they have already done. But we can prevent more examples from being added to this list. Never release fish from your aquarium into the wild. Never buy a fish you can’t house. Never expect someone else to take care of your fish when it gets larger. Speak up if you know someone who wants to release an aquarium fish. They may see it as just one fish, but they don’t know that hundreds of “just one fish” have already led to problems. We all can make a difference, and it starts with just one fish. 

Works Referenced

Deacon, J.E., C. Hubbs, and B.J. Zahuranec. 1964. Some effects of introduced fishes on the native fish fauna of southern Nevada. Copeia 1964(2):384-388.

 

Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D.E. McAllister, and J.R. Stauffer, Jr. 1980 et seq. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, NC.

Leo Nico, Pam Fuller, and Matt Neilson. 2013. Astronotus ocellatus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. nas.er.usgs.gov/ Updated: 4 March 2013. Retrieved: 28 March 2013. 

"Lionfish Pterois volitans." Florida Fish and Wildlife Conservation Commission. http://myfwc.com/wildlifehabitats/nonnatives. Updated: 2013. Retrieved: 28 March 2013. 

"Lionfish Research Program." REEF. www.reef.org. Updated: 2012. Retrieved 28 March 2013.

Moyle, P.B. 1976. Inland fishes of California. University of California Press, Berkeley, CA.

Nico, Leo G., Howard L Jelks, Travis Tuten. 2009. Non-Nativev Suckermouth Armored Catfishes in Florida: Description of Nest Burrows and Burrow Colonies with Assessment of Shoreline Conditions. Aquatic Nuisance Species Research Program 09: 1-29. 

Nico, L.G., P.J. Schofield, J. Larson, and A. Fusaro. 2013. Carassius auratus. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. nas.er.usgs.gov/ Updated: 4 Jan 2012. Retrieved: 27 March 2013. 

"Piranha-like fish caught in Utah Lake was a Pacu." The Salt Lake Tribune. www.sltrib.com. Updated: 21 July 2006. Retrieved 27 March 2013.

Taylor, Fred. 27 Sept 2006. "Wild life experts don't bite on tale of piranha in Lake Gaston." WRAL News. www.wral.com. Retrieved: 28 March 2013. 

Fish in their Natural Habitats

I like my aquariums to replicate the natural homes of fish as much as possible. There is no better way to get an idea of the streams and rivers our tropical fish come from than to visit those streams. But for those of us like myself that don't have the money to do something like that, we can use videos as an alternative. Freshwater enthusiast and Venezuelan native Ivan Mikolji makes those journeys for us and shows us the wonderful natural aquariums that are home to our beautiful aquarium fish.

Is my fish a girl or a boy?

How to determine the sex of your fish

Most people like to name their fish and want to have a name that fits the fish’s gender. Other people want to try breeding and need to know if they have males and females. Sexing fish can be a tricky thing, but there are some species and families of fish that are relatively easy. Before we get into those, I’ll talk about some general trends in sexing fish.

Females are rounder

Of course this only works with mature animals, but for the most part the female will have slightly thicker bodies. This is because the eggs that females carry take up more space than sperm. The females also need larger fat reserves to produce the eggs.

Males are smaller and more colorful

Just as in birds, males are the more colorful of the genders. Males compete with other males by showing off their vibrant colors. The most colorful male gets to mate. They are also slightly smaller than the females.

Sexing popular fish

Goldfish (Carassius auratus auratus)

These fish can actually be a little tricky as they have no obvious differences when the fish are not breeding, but there are two things you can look for when they breed: breeding stars and the shape of the vent.

Breeding stars or breeding tubercules will only appear on the males. They appear on the gill plate and pectoral fins. These are a sign of virility, and a study performed on a relative of the goldfish found a correlation between the number of breeding stars and how healthy a male fish is. These stars help a female fish decide who she wants to mate with.

Breeding stars on pectoral fin and gill cover (goldy fk @ flickr)

The next thing to look for is the shape of the vent (this is also called the cloaca and is the opening near the anal fin). The vent of the male will be slightly larger and concave (meaning it curves inward). The vent of the female will be smaller and protrude slightly. The pictures below better illustrate this.

Circled male vent (mikroll @ TheGAB)

Circled female vent (mikroll @ TheGAB.org)

I find using the vent method to be a little difficult as my goldfish usually like to have their heads facing towards me begging for food. I prefer to use the breeding star method because they are more visible in my experience.

Betta fish (Betta splendens)

These small, popular tropical fish are a little easier than goldfish to sex because some of it can be done out of the breeding season. There are two main ways to sex bettas: fin length and the presence of an ovipositor.

If you see a long-finned betta it is a male. There have been cases where females have longer than normal fins, but they aren’t nearly as long as the typical halfmoon spread seen below.

These extremely long fins indicate a male(Aquariumloto @ Flickr)

Sexing bettas gets a little trickier when you are dealing with plakat (or short-finned) bettas because the male and female fins are the same length. Now you have to look for the ovipositor on the female. The ovipositor is a small white tube protruding from the vent of the female; in breeding she uses this to position eggs. It will appear as a small white dot behind the ventral fins. The lack of such indicates a male.

Arrow points to ovipositor (Stuart Halliday)

Angelfish (Pterophyllum spp)

Another extremely popular aquarium fish, but much harder than bettas or goldfish to sex. They have no discernible differences when they are not spawning, and when they are spawning you have to look very closely to see the only difference:  the males will have a thinner breeding tube which is visible in the vent of the fish. Both males and females have breeding tubes, so the key is to look for the smaller one.

Female angelfish breeding tube (koiangelfish.com)

Male angelfish breeding tube (koiangelfish.com)

Neon tetra (Paracheirodon innesi)

Like angelfish, neon tetra are difficult to sex. The only difference will be in size. The females will be slightly larger and fatter especially when they are ready to breed. Males may show slightly better color, but these differences are so minute that they will likely go unnoticed.

Livebearers (Poecilidae)

These are fish like guppies, platies, swordtails, and mollies. The males and females are very easy to tell apart. There is a large size difference with some females being almost one and a half times the size of the males. The males will have long, flowing fins and are very colorful. Males also possess a modified anal fin called a gonopodium; this is used to transfer sperm to the females. Below you can see two illustrations showing the differences between male and female guppies

General female livebearer characteristics (jabraguppyroom.blogspot.com)

General male livebearer characteristics (jabraguppyroom.blogspot.com)

Cory catfish (Corydoras spp)

Another popular but difficult fish to sex, cories have no highly visible differences between the genders. Females will tend to be the larger ones and look much chubbier when they are breeding, but for the most part males and females look exactly alike.

Bristlenose pleco (Ancistrus spp)

These small plecos are surprisingly easy to sex. Both males and females will have the bristly nose, but the number and size of the bristles will be much greater in the males. This is especially true when the fish are in breeding condition. Scientists believe that males evolved the bristles to mimic young fish because females are more likely to mate with a male who is already caring for eggs.

Male bristlenose with month old offspring (goldy fk @ Flickr)

Oscar (Astronotus ocellatus)

Probably the most popular of the cichlids next to angelfish, but even more difficult to sex. Among wild populations the males show more color than females, but this isn’t reliable with the captive-bred fish that show up in stores nowadays because they have been bred for color.

Cherry barb (Puntius titteya)

This is a species that is easy to sex based on the general trends in fish genders. The males are smaller and have more red color and the females are larger and will be more brown in color. This holds true with wild-caught and naturally bred cherry barbs. There are some that have been specifically bred to make the red even brighter; these are much more difficult to gender. 

Female cherry barb on left, male on right (aquapage.cz)

Gourami

They aren’t as easy to sex as livebearers, but they are pretty easy if you know what to look for. If it’s not a captive-bred variant, the males will be a brighter color especially when breeding. If they are a color variant you have to look for a few other things. For the Trichogaster gourami (this is dwarf, honey, thicklips, and banded) look at the end of the dorsal fin; males will have a pointed dorsal, and females will have a rounded dorsal. These pictures below illustrate this as it can be hard to pick out if you’ve never seen it.

Male honey gourami (CK Yeo @ Flickr)

Female honey gourami (CK Yeo @ Flickr)

For the Trichopodus gourami (opaline, three-spot, blue, gold, pearl, and moonlight) you also look at the dorsal fin. The males will have a longer dorsal fin. Males of the pearl and moonlight species will show more red color than the females.

Pearl gourami. Male above, female below (seriouslyfish.com)

With some of our aquarium fish it can be very easy to tell the males from the females, but others can give you a lot of trouble. Some like oscars and angelfish can even give breeders trouble in determining gender. If you wish to breed any of these fish, I highly suggest you do a lot of research and read personal experiences. While breeding can be fun and rewarding, it can also be costly and heartbreaking when done incorrectly.

Works referenced

Christie F. 2006. Sexing Bettas: The Ovipositor. nippyfish.net. Retrieved: 31 Jan 2013

How to tell Male and Female Guppy Apart. Jabraguppyroom.blogspot.com. Updated: 29 July 2011. Retrieved: 1 Feb 2013.

Kortet R., J. Taskinen, A. Vainikka, and H. Ylonen. 2004. Breeding Tubercles, Papillomatosis and Dominance Behavior of Male Roach (Rutilus rutilus) During the Spawning Period. Ethology 110:591-601.

Seriously Fish

Sexing Angelfish. Koiangelfish.com. Updated: 2013. Retrieved: 1 Feb 2013. 

Sexing Goldfish. Bristol-aquarists.org.uk. Updated: 26 October 2012. Retrieved: 31 Jan 2013

Sexing Goldfish. theGAB.org. Updated: 16 Aug 2009. Retrieved: 31 Jan 2013

Common Beginner Aquarist Mistakes

Okay, so you've gotten your first tank, and it’s fully cycled. Whew. Glad that ordeal is over. But you have to be careful. There are still a few beginner mistakes that will trip up a new fishkeeper. I’ll recount some of the big ones here and ways to avoid them.

Trusting the pet store implicitly

When you are just beginning you get a lot of advice from a lot of people. Some of it will be good, but some of it will be bad. The majority advice will from pet stores will fall under the bad category. The large chain stores like Petsmart and Petco are notorious for this. I can’t tell you how many times I’ve heard someone say “But this is what the lady at Petsmart told me to do,” when I asked why they were doing something wrong.

It’s actually in pet store’s short-term benefit to give bad advice because it leads to stress on the fish. Stressed fish get sick. And where do you buy medications to cure the illnesses? The pet store. So instead of just making money from the tank, the fish, the décor, and the filter, they also make money on the medications. And they sell a lot of them.

So to be safe, double check whatever advice you get from pet stores. For the most part they are thinking about money not your fish.

German blue ram (Mikrogeophagus ramirezi),
beautiful but fragile  (sapienssoultions @ Flickr)

Leaving the light on too long

While this usually won’t kill your fish, it will do your tank more harm than good in the long-run. I’ve heard people say they want to use the tank as a night light, but people often forget that fish need sleep, too. They don’t have eyelids and can’t block out light like we can.

All living thing have a circadian rhythm; this is basically your body’s clock. Scientifically it’s a series of hormonal responses that govern a variety of processes in the body from hunger to the need to use the bathroom. It makes you sleepy before you normally go to bed. It’s how your dog always knows when it’s feeding time. Fish have this, too. Part of the circadian rhythm is the day/night cycle. The circadian rhythms of fish are directly related to the amount of light. These changes in light govern things like metabolism, sleep, and breeding behavior. Sleep in fish is induced by an absence of light much in the same way as with humans. Without a period of darkness the hormones that govern these processes won’t be produced. As a result of this, the fish won’t live a normal existence.

Excess light in the aquarium will also lead to outbreaks of algae. Some algae is normal. No healthy tank is without it. But when it starts to take over the walls and coat the décor, it becomes a nuisance. One of the easiest ways to get rid of algae is to reduce the amount of light coming into an aquarium which usually means reducing the amount of time the tank light is on. This leads me to my next point.

Getting a fish to “clean the tank”

There is no fish that will do this for you. Algae eaters (and not all fish that are advertised as such will eat algae) may physically remove the algae, but it’s not gone. They just convert it into poop. This poop decomposes to become ammonia which is algae fuel. Combine this with the lights being left on too long and you have a recipe for even more algae.

I’ve also seen people get substrate fish like cories and loaches for the purpose of cleaning the tank. They want something to eat the food the other fish miss. But when these fish aren’t given some kind of supplement they often die of malnutrition (yes it is possible to underfeed). All fish in all levels of the aquarium must be fed. Even the true algae eaters like the oto catfish and farlowella catfish need supplements from time to time.

I’ll take this moment as aside to talk about the fish that are commonly sold as algae eaters and the problems most come with. These fish include plecos, Siamese algae eater, Chinese algae eaters, and oto catfish. These fish are often “buyer beware” as the labels in the pet store rarely tell you everything you need to know about them. Plecos only graze algae when they are juveniles and actually become predatory scavengers as they age. The adults need levels of protein similar to most community fish. They often achieve this by latching on to the sides of slower moving fish like discus and goldfish. Some species like the bristlenose (Ancistrus spp) will stay small enough for a regular community, but the fish commonly traded as “common pleco” will get over a foot long and need a very large aquarium. 

Young male bristlenose pleco (public domain)

The Siamese Algae Eater (SAE) is another one that can cause problems as there are three fish traded under this name: true SAE (Crossocheilus langei), false SAE (Garra cambodgiensis), and flying fox (Epalzeorhynchos kalopterus). All of these fish look remarkably similar, but have different behaviors. The true SAE and false SAE are both peaceful provided they are maintained in groups of more than 5 individuals, but false SAE won’t eat algae like the true SAE. The flying fox is the bad apple; they are rather nasty to members of their own species and any other fish that likes to be near the substrate. They hardly ever touch algae. The name of the Chinese algae eater (Gyrinocheilus aymonieri) is rather misleading as it won’t eat any algae either. It’s also rather aggressive and not recommended for either a community aquarium or algae control. Oto catfish are actually very good at keeping an aquarium free of algae, but they are a rather fragile fish and still need supplements to be healthy. 

Overfeeding

It’s another major problem that plagues the new aquarist. Every single time you walk by the aquarium, the fish are at the front, and they’re begging for food. They always look so hungry, and you want to feed them. Just because fish look hungry doesn’t mean you should feed them. It’s a good thing that your fish are acting hungry. A hungry fish is a healthy fish. But overfeeding can change that.

When you overfeed (add more than the fish can consume in a minute) then the extra food sits at the bottom and decays. This releases more ammonia into the water and contributes to the overall nitrate level in the tank. The decaying food will also lower the pH in the tank as well as use up oxygen. Even if you remove the uneaten food, the fish will poop more when they are fed more. This poop will also decay and cause the same problems as uneaten food.

Koi begging for food (Barbara L. Hanson @ Flickr)

“But they always look so hungry.” I know. But fish metabolisms operate much differently than a mammal’s metabolism. Because we have to spend so much energy maintaining our core body temperature we need to eat a lot of food. Fish don’t need half the calories we do because they don’t heat their bodies. In fact, most healthy adult fish can go about 2 weeks without eating and still remain fine.

Messing with water chemistry

I’ve seen a few beginners make this mistake, but not as many as you would think. Sometimes the pet store employees encourage the purchase of products to stabilize pH, and other times people just see them and assume they are necessary because they believe a perfectly neutral pH is essential for fish. In most cases these products are not needed at all and can actually harm the fish by creating a constantly changing environment as they rarely ever stabilize the pH. Fish are adaptable, and many of the best beginner fish will adapt to any pH within a normal range (6.0 – 8.0). Stable water is always safer than water with a rapidly changing pH.

Adding too many fish at once

This is probably the second most common mistake after trusting the pet store. Too many fish added to a tank too fast will cause problems in any tank, even the established tanks of old pros. Adding a lot of fish at once creates a large influx of ammonia. The beneficial bacteria that comprise a cycle don’t replicate that fast and need time to adjust to large changes. In the meantime, the ammonia is poisoning your fish. Whenever you add fish, you will have an increase in ammonia, but if you add them a few at a time, the influx will be small enough that the plants and bacterial colonies can easily take care of it and grow accordingly.

In an uncycled tank, adding a large amount of fish can be deadly. They will be producing ammonia at a fast rate and there will be basically no bacteria to take care of it. Ammonia levels can rise to fatal amounts within a matter of days. This is called new-tank syndrome. It’s easily avoidable by either cycling the tank with a small number of very hardy fish or by cycling the tank before you add the fish.

Harlequin rasbora shoal (Chantal Wagner @ flickr)

The most important thing to remember is this hobby is about patience. I've heard it said that nothing good happens fast. Plants and fish don’t grow overnight and neither do the good bacteria. If you need a “fish fix” in the meantime, join a fish forum and talk to other hobbyists!

Works Referenced

“10 Biggest Mistakes in Fishkeeping.” practicalfishkeeping.co.uk. Updated: 2 December 2011. Retrieved 1 Aug 2012.

Helfman, G. S et al. 2010. The diversity of fishes, second edition. Wiley-Blackwell, Oxford.

Zhdanova, I. V. and S. G. Reebs. 2006. Circadian rhythms in fish. Pages 197 - 238 in K. A. Slowman, editor. Behaviour and Physiology of Fish, vol 24. Gulf Professional Publishing. 

Best and Worst Beginner Fish

I see a lot of people ask “what fish should I start with?” I also see a lot of people starting with fish that they were lead to thinking were easy.  Most people want a tank full of beautifully colored fish. I understand this, but often the most beautiful fish are also much more delicate. However, there are some very pretty and hardy fish with which you can start your hobby. They may not look like much in the store tanks, but once you get them home and into a good setup, they will show their true colors for you.

Through personal experience and discussion with other aquarists, I have gathered a list of fish that are good for the budding fishkeeper. These fish were chosen for their hardiness (ability to survive a cycle and live in less than ideal conditions), adaptability (can live in a wide range of parameters), small size (ideal for the first aquarium), and peacefulness. I have also compiled a list of fish that beginners should avoid for various reasons such as size, aggressiveness, and sensitivity.

Before I go into the fish, let me take a minute to explain what a good first aquarium size is. While bigger is always better, the beginner might not want to start with a massive tank of 55 gallons (209 L) or larger. This is a big tank (and a big expense), and big tanks mean big water changes which a new aquarist might not want. Conversely a 10 gallon (40 L) isn’t a great beginner tank because it is so small, and small tanks can have fast and dangerous water parameter swings. Also you can only fit one or two species of fish in a tank of that size. I’ve come to believe that tanks from between 20 gallons (75 L) and 40 gallons (151 L) make great beginner tanks because they are large enough to be mostly stable but not too large as to be a pain to perform water changes and they enable the first time fishkeeper to keep more than two species. 

The Bad Choices

Many fish that the pet stores tout as easy and great for beginners are far from that for many reasons. Some grow too large, some are hard to keep alive, and some are aggressive. Since there is a multitude of fish that would make poor first choices, I’m going to group them into categories and give you examples of fish that fall into these categories.

The first category of poor beginner fish are chosen because they get so large. They are sold as cute, inch-long babies, but they will soon be busting the walls of a normal beginner aquarium. These fish include goldfish (Carassius auratus auratus), common pleco (Hypostomus plecostomus), oscar (Astronotus ocellatus), and kissing gourami (Helostoma temminkii). Many people are surprised to see goldfish on this list because all you see in the stores are cute little goldfish. Trust me: these little golden wonders will soon be around a foot long and all the while they grow, pooping like a fiend. They are a hardy fish, but they just get too large for most beginners to handle.

You also don’t want to start off with a fish that is too sensitive. Oto catfish (Otocinclus macrospilus), angel fish (Pterophyllum spp), cardinal tetra (Paracheirodon axelrodi), and many more fall into this category. They should never be introduced to a cycling tank (tank where colonies of beneficial bacteria are not established and harmful levels of ammonia and nitrite are present) because they can’t handle the stress of a cycle. Oto catfish specifically need a setup that has had time to grow algae because they primarily eat algae. They come to stores starving because they are captured from the wild where they only eat algae. By the time they get to the store they haven’t seen any in weeks; they will starve to death in a brand new setup because it lacks algae.

Another mistake that beginners often make is buying fish that are too aggressive to keep with much else; they end up with a moderately large tank and nothing in it but a single school of fish. Or they buy a “freshwater shark” because the name sounds cool, and then end up with a tank full of fish cowering in the corner trying to stay away from the shark’s bullying nature. If you just want to keep a school of these fish or a freshwater shark, then go right ahead, but you won’t be able to add anything else to the tank. Fish that fall into this category are tiger barbs (Puntius anchisporus), black skirt tetra/black widow tetra (Gymnocorymbus ternetzi), and the freshwater sharks like rainbow shark (Epalzeorhynchos frenatus), bala shark (Balantiocheilos melanopterus), and red-tailed shark (Epalzeorhynchos bicolor).

Guppies (Poecilia reticulata) are a great beginner fish, right? You’d be surprised to learn that they are not. They were many years ago, but commercial scale breeding and continuous inbreeding has made what was once an extremely hardy fish into a weak, disease-ridden fish terrible for beginners. If you can find guppies from a hobby breeder, then you have the chance to get some good fish, but pet store guppies are so weak, they can hardly be considered a good fish anymore. Sadly, neon tetra (Paracheirodon innesi) and dwarf gourami (Trichogaster lalius) have also gone down this same route. Commercial-scale breeding programs are now producing weak, inbreed, and disease ridden fish. In fact, both fish now have a disease named after them because these fish so commonly carry them: dwarf gourami iridovirus and neon tetra disease. These diseases have no cure and can spread to other species.

I know you want to start off with strange and unusual fish to wow your friends, but these fish are usually delicate, difficult to keep alive, and have specific needs. This brings me to my final category of fish that are bad for beginners: the oddballs. These are fish like the black ghost knifefish (Apteronotus albifrons), German blue ram (Mikrogeophagus ramirezi), and African butterfly fish (Pantodon buchholzi). A good rule of thumb is if it looks strange, it’s going to be hard to keep alive. 

The Good Choices 

Don’t despair. While those are fish you shouldn’t start with, you have plenty of attractive and interesting options that can be your first fish. Instead of grouping them like the bad beginner fish, I have listed them out with pictures and general care information. All of these fish are not picky eaters and will readily accept any flake or pellet food.

Blue Tetra (Catxx @ the Aquarium Wiki)

Blue Tetra, Cochu (Boehlkea fredcochui)

Tank size: 20 gallons, 24 inches long (75 L, 61 cm)

Temp: 72 - 79F (22 - 26C)

pH: 6.0 - 8.0

Water hardness: up to 15 dGH

Notes: Like most tetra species this is a schooling species and needs to be maintained in groups of 6 or more. When buying schooling fish like this it is best to buy about 9 so in case you have a death, these fish won’t start bullying other fish. Don’t keep them with fish with long fins like betta fish. This fish will be most colorful in an aquarium with lots of cover such as decorations and plants (live or fake).

Group of Flame Tetra (Catxx @ the Aquarium wiki)

Flame tetra, Fire tetra, Von Rio tetra (Hyphessobrycon flammeus)

Tank size: 20 gallons, 24 inches long (75 L, 61 cm)

Temp: 72 - 82F (22 - 28C)

pH: up to 7.8

Hardness: up to 25 dGH

Notes: This is another gorgeous and hardy tetra species. They should be kept in a minimum of 6, but keeping them in larger numbers will make them more attractive and reduce the nipping tendencies common with tetra. Don’t keep them with slow-moving fish. It will show its best colors in an aquarium with lots of decorations such as fake or live plants.

X-ray tetra (Debivort @ Wikipedia)

 

Pristella tetra, X-ray tetra, X-ray fish, Goldfinch tetra (Pristella maxillaris)

Tank size: 10 gal, 20 inches long (40 L, 50 cm)

Temp: 74 - 82F (24 - 28C)

pH: up to 8.0

Hardness: up to 30 dGH

Notes: In my opinion, this is one of the best beginner fish because it is so easy to keep. It will survive in all but the most hard of municipal water supplies. Like all tetra, it should be kept in groups of 6 or more at a minimum.

Bronze cory cats (public domain)

Bronze Cory Cat, Albino cory (Corydoras aeneus)

Tank size: 20 gal, 24 inches long (75 L, 61 cm)

Temp: 70 - 80F (21 - 27C)

pH: 6.0 - 8.0

Hardness: up to 20 dGH

Notes: Also found in an albino form, the bottom-swimming bronze cory is a great addition to a new fishkeeper’s aquarium. They will do best with a sand bottom but can manage with smooth gravel. It will be most active when kept in groups larger than 5. Three is the minimum that should be kept together as these fish are very social.

Two harlequin rasbora (Stee @ flickr)

Harlequin Rasbora, Red rasbora (Trigonostigma heteromorpha)

Tank size: 20 gal, 24 inches long (75 L, 61 cm)

Temp: 70 - 82F (21 - 28C)

pH: below 7.5

Hardness: up to 15 dGH

Notes: A common fish in pet stores, it is a great choice for a beginner. This is another social fish that needs to be maintained in groups of 6 or more, but it will fare best with groups of 10 or more.

Two Bandit cories (Stuart Halliday)

Bandit cory, Masked cory (Corydoras metae)

Tank size: 10 gallons, 20 inches long (40 L, 50 cm)

Temp: 70 - 77F (22 - 25C)

pH: up to 7.5

Hardness: up to 15 dGH

Notes: As they are more shy than bronze cories, they should be kept in groups of 6 or more. They will be much more active in larger groups. When kept singly or with 1 or 2 other bandit cories, they will not be seen much and may be too shy to feed. They like a sand bottom best as they enjoy rooting around in the sand for morsels of food.

Regular zebra fish (public domain)

Glofish, genetically modified zebra danio (www.glofish.com)

Zebra danio/glofish (Danio rerio)

Tank size: 20 gallons, 24 inches long (75 L, 61 cm)

Temp:  65 - 77F (18 - 25C)

pH: 6.0 - 8.0

Hardness: up to 20 dGH

Notes: Also sold as the brilliantly colored glofish, these peaceful little schoolers make a much better candidate for a smaller unheated aquarium than goldfish do. The zebra danio that are sold as glofish aren’t dyed. They are actually genetically engineered to be that way by having jellyfish and coral genes implanted in their own. They will pass this down to their children, too. Like all schooling fish, these active little swimmers need at least 6 of their own kind to feel safe (you can mix glofish and the regular zebra danio). As a precautionary, I feel like I need to mention that due to massive inbreeding, this fish are becoming less and less hardy; one day they might not be good beginner fish.

Glowlight tetra (gonzalovalenzuela @ flickr)

Glowlight tetra (Hemigrammus erythrozonus)

Tank size: 20 gal, 24 inches long (75 L, 61 cm)

Temp: 74 - 82F (24 - 28C)

pH: up to 7.5

Hardness: up to 15 dGH

Notes: Like all the other tetra, this little beauty is a schooling fish and should be kept in groups of at least 6, but if you have the room and biological capacity add as many as you can. They are most colorful in large groups. An albino form is also seen and is just as hardy as the normal form. The albinos will school with the regular glowlights.

School of bloodfin tetra (public domain)

Bloodfin tetra (Aphyocharax anisitsi)

Tank size: 20 gal, 24 inches long (75 L, 61 cm)

Temp: 64 - 82F (18 - 28C)

pH: 6.0 to 8.0

Hardness: up to 30 dGH

Notes: This fish gets my vote as the best beginner species. It can survive a wide range of water parameters and is commonly found at petstores. Kept in groups of 6 or more, its brilliant red fins will sparkle in the water.

Male cherry barb (Sannse @ wikipedia)

Cherry Barb (Puntius titteya)

Tank size: 20 gallons, 24 inches long (75 L, 61 cm)

Temp: 74 - 81F (23 - 27C)

pH: 6.0 to 8.0

Hardness: up to 20 dGH

Notes: Barbs, like tetra, need groups of 6 or more to feel safe. They will be more colorful and be out in the open more if they have large groups. Unlike the tetra, the males are more colorful than females. The males have a much more red color while the females take on a yellow-brown hue.

Male swordtail on left; female on right (MacAnthony @ flickr)

Swordtail (Xiphophorus hellerii)

Tank size: 29 gallons, 30 inches long (109 L, 76 cm)

Temp: 68 - 82F (20 - 28C)

pH: 7 to 8

Hardness: 9 - 30 dGH

Notes: As this fish is a livebearer it is the best choice for a new aquarist with hard water. The catch is, if you put males and females in a tank together, you will get more swordtails. If you don’t want baby fish, get only males. If you want baby fish, make sure there are 3 females to every male. Males are also the more attractive of the sexes, so an all-male tank would be ideal for a beginner. Pretty and you don’t have to worry about babies.

These next two fish are good beginner choices, but they come with a catch which I will highlight in italics.

Male betta (copperarabian @ deviantart)

Betta fish/Siamese Fighting Fish (Betta splendens)

Tank size: 5 gallons (18 L)

Temp: 76F - 84F

pH: 6.0 - 8.0

Hardness: up to 20dGH

Notes: Betta fish are a great first fish if they are the only fish in the tank. They are very hardy, easy to care for, and will generally take any beginner mistakes in a stride. Their small tank requirement also makes them great as a dorm pet. Due to their aggressive nature, keeping betta with other fish makes the difficulty go up and can be a bit much for a new fishkeeper. Keep him in his own 5 gal tank and you will have an easy setup with a very interactive fish.

Male honey gourami (Kooshking @ flickr)

Honey gourami (Trichogaster chuna)

Tank size: 20 gal, 24 inches long (75 L, 61 cm)

Temp: 72 - 82F (22 - 27C)

pH: 6 - 7.5

Hardness: up to 20 dGH

Notes: This little jewel is the smallest and most peaceful of the gourami. It will make a great centerpiece fish in a small tank provided it is the only gourami in the tank. This also includes bettas as they are gourami, too. Male gourami are territorial and will fight when placed in the same tank. The males are the most colorful, so just one would be the perfect addition to a beginner’s tank.

Don’t feel limited by what the pet stores tell you are good beginner fish (because they are often wrong). The beginner has many attractive options for their first fish tank. As I discuss in my How to Stock a Fish Tank article, combining a species of cory cats and a school of tetra in a 20 gal tank could make a very nice display for the first-time aquarist. While not all of these fish may be available at your local pet store, I’m sure you will be able to find some of them to help you get started in your fishkeeping hobby.

Works Referenced

Monks, Neale. 2008. “Fish Viral Disease.” www.fishchannel.com. Retrieved 28 May 2012.

Monks, Neale. 2011. “Neon Tetra Disease.” www.fishchannel.com. Retrieved 28 May 2012.

Ramsey, Graham. 3 March 2010. “Top Ten – worst beginner fish.” fcas.wordpress.com. Retrieved 27 May 2012. 

Be careful of that label!

Why research is always needed before a fish purchase

When the average first time aquarium keeper walks into a pet store, they completely trust the employees there. Sometimes that trust is well placed, and the budding aquarist walks out with a 29 gallon (109 L) tank, some lovely X-ray tetra (Pristella maxillaris), and a water parameter testing kit. Other times, the new (and soon to be disappointed) aquarist walks out with a 20 gallon (75 L) tank, a pleco, an oscar, and—worst of all—a black ghost knife fish. (If you didn’t cringe at that, don’t worry, you soon will.)

In this particular article I’m going to be using Petsmart and Petco as examples simply because I know these stores best. They are the large chain pet retailers that I have closest to me. This is in no way intended as a stab at these stores because while there is a lot of bad information, they also have some proper information on the labels of the fish they sell. I am highlighting particular instances where the label is grossly wrong as an example of why research is needed or you may end up with more than you bargained for.

Clown Loach (Chromobotia macracanthus)

As adults, the vibrant colors of clown loach fade (Public Domain)

I’m going to start with my favorite fish of ones I’m highlighting today: the clown loach. Entertaining and active, these guys would make a great addition to your home aquarium, right? Wrong. Like so many of these tankbuster species, the little clown loaches you see at the store are babies. Probably less than a few months old. Now let’s compare Petsmart’s and Petco’s care advice for these species versus the advice from the loach experts over at Loaches Online.

	Loaches Online	Petsmart	Petco
Min tank size	180 gal (680 L)	40 gal (150 L)	50 gal (190 L)
Adult Size	12 inches (30 cm)	12 inches (30 cm)	12 inches (30 cm)
Hardness	1-12 dGH	NOT SHOWN	NOT SHOWN
pH	6.5 - 7.0	NOT SHOWN	6.0 - 7.5

As you can see there are some major discrepancies. Loaches Online’s veteran clown loach keepers recommend the smallest tank juveniles (which are what is sold in stores) be housed in is a 55 gallon (208 L) tank with biweekly water changes because these fish are active swimmers and any less will cause stress and stunting, but this should only be temporary housing. And the fact that some of the parameters such as pH and hardness aren’t even given in the Petsmart and Petco labels is also unsettling as the wrong pH and hardness can stress a fish to death. Sadly, I found this to be a constant with the Petco and Petsmart labels. Another surprising constant I found through the Petsmart and Petco care sheets was proper temperature for these fish, but this is only part of what is needed to keep a fish healthy. You can’t complete a puzzle without all the pieces.  

Fortunately, if you like the look of this fish there are some loaches that stay small enough to fit in the average home aquarium. The yoyo loach (Botia almorhae), angelicus loach (Botia kubotai), zebra loach (Botia striata), and Burmese loach (Botia histrionica) all have a similar shape and personality to the clown loach. If you search by the scientific name, you can find pictures of these cute, colorful fish. The only difference between these guys and the massive clown loach is that these guys can safely live their complete lives in a 50 gallon (190 L) tank which is a much more common and manageable size home aquarium.

Pleco, Plecothemus (Hypostomus plecostomus)

Mature pleco (Derek Ramsey @ Wikipedia)

The main reason people buy this fish is for its algae-eating abilities (I will go into why this is bad in a later article). Yes it does eat algae when small, but as it grows it begins to also eat lots of protein. This can easily mean small fish; it has also been known to attach to larger slow-moving fish like goldfish (Carassius auratus auratus).  Let’s compare what the expert fish keepers over at Tropical Fish Keeping.com have to say about plecos versus the Petsmart and Petco labels.

	Tropical Fish Keeping	Petsmart	Petco
Min tank size	55 gal (208 L)	55 gal (208 L)	10 gal (38 L)
Adult size	20 inches ( 50 cm)	24 inches (61 cm)	24 inches (61 cm)
Hardness	Less than 28 dGH	NOT SHOWN	NOT SHOWN
pH	6.0 – 8.0	NOT SHOWN	NOT SHOWN

While Petsmart did get the sizing right, I still see the associates selling these fish to anyone who asks for an “algae eater.” On the other hand, Petco falls very short here. Pleco need large tanks not only because of their size but also because they produce a lot of ammonia relative to body mass. They are comparable to goldfish in the amount of fecal matter and ammonia they produce. Again, neither of the chain stores mentions hardness or pH, two essential elements for keeping fish healthy.

Fortunately if you like the look of plecothemus, it has some relatives that can easily fit in your aquariums. The bristlenose pleco (Ancistrus sp) is similar in appearance and behaviour but only grows around 4 inches (10 cm) long. A single individual can be housed in a 10 gallon (38 L) tank or a pair in a 20 gallon (75 L). Groups need a 50 gallon (190 L) or larger tank as males can be territorial.

Black Ghost Knifefish (Apteronotus albifrons)

Juvenile black ghost knife fish
(Derek Ramsey @ Wikipedia)

While this is an interesting and unusual fish, this is a fish best left to be admired in public aquaria. Due to its large size, timid nature, and unique biology, this is not a good home aquarium fish, but it is still sold as such. Let’s compare Petsmart’s suggested care to a knowledgeable fishkeeping site’s care.

	Tropical Fish Keeping	Petsmart
Min tank size	180 gal (680 L)	75 gal (284 L)
Adult size	20 inches (51 cm)	20 inches (51 cm)
Hardness	5- 15 dGH	NOT SHOWN
pH	6 – 8	NOT SHOWN

Due to the manner in which these fish use electricity, their spines are inflexible. They must have an aquarium that is at least three times its length and twice as wide as the fish is long.  A regular 20 inch (51 cm) fish could hardly fit in a 75 gallon (284 L) aquarium let alone a fish with an inflexible spine. As with so many other species, Petsmart is falling very short on its care. At least Petco doesn’t carry this species.

For those looking for an alternative fish that still maintains the strange look of a knife fish, the African knifefish (Xenomystus nigri) is a good alternative that can be housed in a 55 gallon (208  L) tank. As all knifefish are rather delicate, this fish is not for the beginner aquarist and should be housed in a specialized setup. It is not for your typical community tank. Extensive research is suggested before buying this fish.

Pangasius catfish (Pangasius sanitwongsei)

Adult captured in Thailand (Matt Leete @ Fishbase.org)

Sometimes sold as an iridescent shark or paroon shark, they may look cute as babies at the store, but this is a species that is wholly unsuited for even public aquaria. A close relative of the massive Mekong giant catfish (Pangasianodon gigas), one of the largest freshwater fish in the world, any store that sells this fish and claims it can live comfortably in a home fish tank should be ashamed. This is a massive migratory and skittish species known for slamming into the tank walls when frightened. With specimens tipping the scales at 660 lbs (300 kg), a single fish could easily crack or break a tank wall.

	Seriously Fish	Petsmart
Min tank size	500 gal (1892 L)	75 gallons (283 L)
Adult size	48 inches (1.2 m)	25 inches (61 cm)
Hardness	2 – 30 dGH	NOT SHOWN
pH	6.5 – 7.5	NOT SHOWN

As you can see in this case, Petsmart falls very short of the care requirements of this species. Practical Fishkeeping is part of a movement called The Big Fish Campaign to spread awareness about this species and the other tankbusters like the tiger shovelnose catfish (Pseudoplatystoma spp), red tailed catfish (Phractocephalus hemioliopterus), and giant gourami (Osphronemus goramy). If you buy this fish and think you will just get a larger tank as it grows, think again. This species is known to live for 20 or more years and will need a tank as large as a medium moving van. And most public aquaria won’t take them when they outgrow your tank. This species is beyond their capacity to house long-term.

As you have seen, these two major pet retailers fall very short on their care sheets for these species. Many of these care sheets also cite the “gallon per inch of fish” rule which aquarists have known to be a poor stocking tool for a long time. Think about it this way, 10 inches of neon tetra aren’t the same as 10 inches of oscar. The 10 inches of neon tetra could easily be kept in a 10 gallon tank, but a 10 inch oscar would hardly be able to turn around. This rule doesn’t hold water when looking at fish larger than an inch or two because it doesn’t take into account the fish’s depth as fish grow in three dimensions, not just one. To be safe, I wouldn’t stock any tank based on this “rule.”

The only rule you can use to stock a fish tank is research, research, research. I hope these comparisons have opened your eyes to the need for it. I know there are many people who instinctively trust retailers, but as you have seen they cannot always be trusted to give you the correct information on your fish and in many cases are just trying to make a sale. In fact, telling you a fish needs a smaller tank that it should be housed in will cause the fish stress; stress leads to disease; and diseases are cured by medication bought from the store. See a pattern here? Always research before you buy!

Works referenced

Craig, Nicolette. 24 March 2011. “Who’s to blame for the big fish problem?”  www.practicalfishkeeping.co.uk. Retrieved 11 May 2012.  

Gay, Jeremy. 27 January 2012. “Will you support the Big Fish Campaign?” www.practicalfishkeeping.co.uk. Retrieved 11 May 2012. 

Hill, Nathan. 8 March 2012. “Where do all the big fish keep going?” www.practicalfishkeeping.co.uk. Retrieved 12 May 2012.

Monks, Neale. 2009. "Knifefish in the Aquarium." Tropical Fish Hobbyist (June): 86-90.

Fish Profiles referenced on 14 May 2012:

Clown Loach

• Petsmart
• Petco
• Loaches Online

Plecostomus

• Petsmart
• Petco
• Tropical Fish Keeping

Black Ghost Knifefish

• Petsmart
• Tropical Fish Keeping

Pangasius Catfish

• Petsmart
• Seriously Fish