Selecting Community Tank Fishes, For Dummies

Almost everybody who starts off in the fish-keeping hobby starts with a community tank. That is, an aquarium where more than one species of fish are kept. Even as an advanced hobbyist, if you have one aquarium in your living room, its a good bet that that it’s a community tank too. So you would be hard-pressed to find a club member that doesn’t have at least one community aquarium right now, and I would be willing to bet you can’t find a single member who hasn’t set up at least one in the past.

So, say you are a neophyte aquarist arriving home with a brand new aquarium and would like to follow the time-honoured tradition and set it up as a community tank. How do you select your fish?

As a novice, you are most concerned about having the fish live, and consequently want to choose hardy fish. You don’t want to choose fish that are expensive either, since inevitably there will be at least some deaths. And you want fish to be colourful and active, but not fight with one another.

Thankfully, your choice is wide, and you can have a nice collection of fishes if you follow some basic advice. What fish do you buy? Well, personal taste obviously comes into play, but I can offer some highly opinionated advice. Other club members will give you other suggestions. Hopefully however, I will try to explain the guidelines and principles used when selecting community fishes, so you can apply them when making your own decisions. Or if you want to just follow my advice like a prescription, the choices I present here will work together nicely and give you a fine display.

First and foremost, read more than just this article. You need to be familiar with the basics of proper filtration, and the proper way to introduce fish and allow time to cycle the tank before going ahead. The CAS library has many books on these aquarium basics, and last month’s issue of The Calquarium has an article in it called “Setting Up A Tank, For Dummies”. The aquarium newsgroups’ frequently asked question (FAQ) pages are also a highly recommended source. Find them on the Internet at

So, you did your homework and have now set up your tank, complete with lights, plants, and suitably matured filters. Time to go back to the fish store.

What fish you buy depend largely on the size of tank you have. Most beginners’ tanks are smallish, 50 litres to 200 litres in capacity. Anything much smaller than 50 litres really can’t give you an eye-catching living room display, but instead would be suitable for a smaller room such as a child’s bedroom. Lets assume you have about 120 litres, a size I would recommend as being easily available, affordable, and still providing enough capacity to provide a stable, easily maintained environment. A slightly larger tank is also very nice, but you should still put the same small number of fish in the bigger tank. Don’t feel compelled to stuff more fish into a bigger tank simply because you can. It won’t look any better than a sparsely populated tank.

The next piece of advice is to never put two fishes together if one has a mouth large enough for the other to fit into. This is pretty basic advice, but many novices still lose their fish to predation. For example, some species of catfish are notorious predators but are still purchased by unsuspecting beginners. The pictus cat, (Pimelodella pictus) is a good example of a popular catfish that simply can’t be trusted with small fish. (If you want catfish and are worried about potential predation, just stick with plecos, Corydoras, and related species to be safe).

The first thing you should look at is a group of schooling fish. The danios are excellent fish for this, and will spawn easily if you decide to try breeding them in the future. If you want smaller fish, any of the smaller danios (like the ever-popular zebrafish, Danio rerio) are excellent, but a 120-litre or larger tank gives you room for one of the larger danios instead, and these are in my mind much more impressive fish. Now, here’s the third piece of advice. These are schooling fish, so buy a school of fish. That means at least six fish, and ten is better. Do not buy just two or three (or one) danios. Two danios alone in a tank will never feel comfortable or behave naturally. Having a large numbers of one fish species does however require that you have fewer species of fish. But believe me, a tank with twenty fish of three species looks much more natural than a tank with twenty fish of ten species.

In a 120-liter or larger tank you can have a second fish school as well. How about six rosy barbs (Puntius conchonius), or any of their medium size relatives? I would however avoid tiger barbs (Capoeta tetrazona) because they are more aggressive and may nip fins. Another possibility is any of the rainbow fishes. The Boeseman’s rainbows (Melanotaenia boesemani) and the red rainbows (Glossolepis incisus) are both very good choices because they are very colourful and not too expensive. Get at least six fish for the second school too.

You now have chosen twelve or so medium-sized schooling fish in your tank. All of the fish offered as choices so far stay near the middle level of the tank, but you would like to make use of the upper and lower levels too. Filling the lower levels is relatively easy, since there are lots of good beginners’ bottom feeders, but suitable top feeders are harder to find. No top feeder fits our criteria of being colourful, cheap, and hardy. The hatchet fishes (Carnegiella spp.) might suffice but I would not consider them hardy. The African butterfly fish (Pantodon buchholzi) is hardy, but relatively expensive. However the popular live-bearing swordtails and platies (Xiphophorus spp.) will spend a lot of time near the surface, and can be used to make better use of the upper level. Personally, I have a bias against unnaturally coloured fish strains (red swordtails and their ilk), but you can still find wild-type “green” swordtails in most good aquarium stores (and various club members breed them as well) so if you share this bias you can still have your swordtails. Get one male and a couple of females. I would not recommend mollies for this tank because these fishes are really quite delicate and are not in my opinion suitable for a novice.

For bottom feeders, get a school of six Corydoras catfish (Corydoras aeneus is a good choice since it’s commonly available and inexpensive) and also add a bristle-nose catfish (Ancistrus spp.) to eat algae. And since no tank is complete without cichlids, a pair of kribs (Pelvicachromis pulcher) completes the population. Make sure the kribs have a cave to hide in. Once together, this selection of fishes will make a colourful, active (but not frenetic) display.

You may have noticed that I have only suggested getting six species of fish for this tank. Many community tanks have much more that that, and that’s fine, but I am sticking to my suggestion to have a relatively small number of species. I think that the hardest thing to learn about setting up an attractive display tank is restraint. A modest choice of fish species invariably results in a more elegant aquarium than does a hodge-podge of species.

You may have also noticed that the collection of fish presented here is a bit eclectic in that the fish come from many different parts of the world. This was done on purpose, because if you restrict yourself to fishes from only one locality you will have troubles finding enough species to populate your tank with hardy, colourful, inexpensive, and peaceful fish. But after you advance in the hobby, you may decide to become a purist and only select fish from one location for your next display tank. Such a tank is called a biotope community, and is the favoured type of community of many advanced aquarists. I have included several possible biotope communities in the suggestions below, but some of the fish listed in the biotope communities are relatively expensive or delicate, and may not be suitable for a novice. Communities that contain such fish are listed below as “advanced”. I have however selected only fish that are readily available in Calgary’s better aquarium stores.

You may have also noticed that I never mentioned anything about water chemistry (pH and hardness) in this article. This too was intentional. It is true that many of the fish mentioned so far come from quite different waters than the moderately hard, alkaline water that comes out of a Calgary tap. However, all of these fish have been bred, raised, and thrive just fine in Calgary’s water. Don’t worry about pH; in fact, in a perverse way, our water is of benefit to the novice who is merely trying to keep a tank of inexpensive common fishes alive and healthy, rather than breeding the latest exotic import. Since our water is so well buffered, you are very unlikely to see any pH changes in your aquarium. A stable (albeit high) pH is much better than a lower pH that is technically within the fishes’ natural range, but constantly changes because fish wastes and other pollution are confined to their small environment.

Here are some suggestions for community aquaria of different sizes designed for aquarists of different levels of experience.

1) A novice’s medium-sized tank (120 litres to 200 litres) housing a mixed community of hardy, inexpensive, active, medium-sized fishes:

One male and two female swordtails. Two schools of six to ten fish each, chosen from: giant danios; rosy barbs; gold barbs; cherry barbs; Boeseman’s rainbowfish; or red rainbowfish. Six Corydoras. One Ancistrus.

2) A novice’s medium-sized tank (120 litres to 200 litres) housing a mixed community of hardy, inexpensive, quiet, medium-sized fishes:

Two male and four female pearl gouramis. Two male and four female dwarf gouramis. Six angelfish. Six Corydoras. One Ancistrus.

3) A novice’s small-sized tank (40 litres to 80 litres) housing a mixed community of hardy, inexpensive, active, small-sized fishes:

One male, and two female swordtails. Two schools of six to ten fish each; chosen from: zebra danios; small tetras; or white clouds. Six Corydoras. One Peckoltia.

4) An advanced aquarist’s medium-sized tank (120 litres to 200 litres) housing an Amazonian community of peaceful, small to medium-sized fishes

Six hatchetfish (delicate). Six angelfish. A school of six to eight medium-sized tetras (e.g. bleeding hearts). Six Corydoras. Six Otocinclus (delicate). One black ghost knifefish (requires night feeding and a hiding place).

5) An advanced aquarist’s medium-sized tank (120 litres to 200 litres) housing a West- African community of peaceful, medium-sized fishes

One pair African butterfly fishes (moderately expensive). Twelve Congo tetras (moderately expensive). One elephant-nose mormyrid (expensive and requires a fine sand bottom and a diet of live tubifex). Two pair of kribs.

6) An advanced aquarist’s medium-sized tank (120 litres to 200 litres) housing a Lake Tanganyikan community of relatively peaceful, smaller to medium-sized fishes. (Note, this tank should be almost filled with rocks, and have well rooted-plants with protection around their bases).

Six Neolamprologus elogatus (formerly N.brichardi). Six Neolamprologus leleupi (moderately expensive). Six Julidochromis marleri or six Tropheus moorii (expensive). Two Synodontis multipunctatus (expensive).

7) An advanced aquarist’s medium-sized tank (120 litres to 200 litres) housing a Lake Malawian community of relatively peaceful, medium-sized fishes. (Note: this tank should have open sandy areas and some rocks among the plants).

Six electric yellows (Labidochromis caeruleus). Six electric blues (Sciaenochromis fryeri) (moderately expensive). Six blue dolphins (Cyrtocara moorii) (moderately expensive) or peacocks (Aulonocara species).

8) A novice aquarist’s medium-sized tank (120 litres to 200 litres) housing a Lake Malawian community of colourful, somewhat aggressive, medium-sized fishes. (Note, this tank should be almost filled with rocks, and have only well protected plantings of Vallisneria or other tough, inedible plants).

Six orange zebras (Pseudotropheus estherae). Six Labeotropheus trewavasae. Six Pseudotropheus socolofi.

9) An advanced aquarist’s medium-sized plant tank (120 litres to 200 litres) housing a mixed community of algae-eating fishes. (Note: this tank’s main feature would be its plants, with just a small collection of fishes).

Twelve mollies. Six Corydoras. Two Farowella cats. Two Ancistrus. Six Siamese algae eaters (Crossocheilus siamensis).

10) An advanced aquarist’s large tank (600 litres or more) housing larger Amazonian fishes. (Note that the only plants in this tank could be Vallisneria or other tough plants with protected roots, and floating plants.)

One silver arowana, Six Geophagus braziliensis. Six Satanoperca leucosticta (requires a fine sand bottom). Twenty Leporinus or Prochilodus (expensive). Five Ancistrus. One large Hypostomus. ?