The Mbuna Community Tank

by Grant Gussie, CAS

originally published in The Calquarium Volume 41, Number 4, December 1998

The African rift lake, Lake Malawi, has an estimated 1000 species of cichlids within it, or almost as many cichlid species as are found in the rest of the world combined.

Lake Malawi’s water is virtually identical (chemically) to Calgary’s tap water – moderately hard and alkaline. Its vast array of fishes therefore adapts readily and easily to local water conditions. That a giant tropical lake in Africa has water so similar to the Bow River’s Rocky Mountain melt-water is just one of life’s happy coincidences.

Furthermore, all Lake Malawi cichlids are maternal mouthbrooders, and few of them present any real difficulties in captive propagation. In fact, Lake Malawi cichlids (with very few exceptions) have proven themselves to be among the easiest of aquarium fish to breed. So soon after a colorful new Lake Malawi cichlid arrives from Africa, local breeders make sure it becomes readily available. Remember how quickly the yellow Labidochromis caerulus became so common in local stores during the early 90’s, and how quickly Pseudotropheus saluosi filled CAS auction bags in just the last couple of years.

Such a huge and rapid increase in availability does of course result in an equally rapid drop in purchase price. Lake Malawi cichlids therefore offer the best value for dollar among the world’s truly colorful fresh water aquarium fish.

The chemical similarity of Calgary and Lake Malawi water and the great value that Lake Malawi cichlids represent means that anyone wishing to set up a spectacular community display of largish fish can do it most easily and cheaply with Lake Malawi cichlids. So…you decide you want a nice big community tank full of colorful Lake Malawi cichlids…something to really draw attention. How do you go about it?

Well, first of all, you are going to have decide which cichlids you want. The Lake Malawi cichlids can be subdivided into three major groups; the mbuna (pronounced um-BOO-nuh), the non-piscivores, and the piscivores. Except for only a few exceptional species (which I’ll get into later), you really should keep these groups separated. Mixing mbuna with non-piscivores generally results in terrorized (or dead) non-piscivores, and most of the piscivores just get too big and mean to be mixed with anything else.

Lets take a look at the most popular, readily available, and easily bred group of Lake Malawi cichlids, the mbuna.

The mbuna are rock-dwelling fish. The group includes the fish in the genera Pseudotropheus, Labeotropheus, Melanochromis, Labidochromis, Petrotilapia, and a few others. Some of the most colorful fish in the world are in this group, and both the female and the male mbuna may have brilliant colors.

But the problem with mbuna is that they tend to kill each other.

The easiest way to keep mbuna’s natural aggression from resulting in death is to keep the fish crowded. Having only a small number of mbuna in a tank always result in the death of the least-dominate fish. So never have less than six fish of any one species, use a tank of at least 200 liters size, and double the usual stocking limit of your aquarium. To compensate for the crowding you have to have very heavy biological filtration, provide lots of water movement, and change a lot of water. A 50% water change twice a week is barely adequate, so anyone trying to keep an mbuna aquarium without a Python or similar water changer is crazy. I would also only recommend a wet/dry biological filter or (ideally) a plant filter for an mbuna tank. A large canister filter is a reasonable alternative (especially one attached to a biowheel) but undergravel filters have no place in a crowded tank of large digging fish.

We also have to supply the mbuna aquarium with a lot of hiding places. Since mbuna naturally inhabit rocky reefs, the mbuna community tank should have lots of rock piles with numerous holes and cavities. So much for your spectacular display, right? OK, so rock piles don’t make for the most beautiful of tank décors but you’re sort of stuck with them. However, you can still try to make the tank as attractive as possible. Local landscaping supply places will sell you rundle stone, a slatey limestone that is perfect for aquascaping the mbuna tank. Its dark color is quite attractive and its building block structure allows you to make numerous caves that will not fall over at the slightest touch. I would suggest building a grotto by covering the sides and the back of your aquarium with a "cliff" of rundle stone, along with several outcroppings and "islands".

In my opinion, all display aquaria should be planted. Fortunately, mbuna are not the least bit light shy and will happily swim under the bright lights that the plants require. Use at least 1 watt of fluorescent or metal halide lighting for every 2 liters of tank capacity. Since no reasonably priced tank top supplies this much light, you are forced to build your own top. Sorry.

Unfortunately, mbuna will eat most plants. About the only plants I can keep in mbuna tanks are Vallisneria. All others are either too slow growing to avoid being smothered by hair algae in the brightly lit, crowded mbuna aquarium, or else the mbuna will just eat them. I think this is unfortunate because I have never particularly liked the looks of Vallisneria. But Vallisneria is however an ideal plant in other ways. It is common in Lake Malawi itself so contributes to a natural looking environment for your fish. It is also one of only a few aquatic tropical plants that does best in the alkaline water that mbuna require. But because mbuna dig, it is necessary to protect the plants’ roots with a plastic "egg crate" light diffuser of the type sold to cover fluorescent light fixtures.

When you choose your tank, choose one as big as possible. The absolute smallest size I would suggest is 200 liters, but at least 400L is much better. If you want to keep the larger mbuna of the genus Petrotilapia then 400 liters is the bare minimum. Also, longer is better. A long tank will give a harassed fish room to get away from any despotic cave owners. Try to get a tank at least 1.2m long, but double that is ideal.

To aquascape your mbuna aquarium, place a level layer of fine gravel or coarse sand about 7cm deep over the bottom of the aquarium (you may wish to mix some laterite or earthworm castings in the lower third of the gravel). Cut the egg crate to completely cover the gravel layer. Then take your Vallisneria plants and individually stick their bottoms through the egg crate holes, and lay the egg crate over the gravel so the plant roots are under it. You’ll want about one plant per liter of tank capacity, but Vallisneria reproduces so quickly with runners that you need not start out with that many. Next take your rundle stones and build your grotto on top of the egg crate (but not on top of your plants off course). The egg crate and gravel protects the tank bottom from damage while keeping your fish from digging under the rocks. After the rocks are in place, add enough additional fine gravel to bury the egg crate.

I would ignore the usual advice for stocking an aquarium with one or two fish for the first six weeks then adding only a few fish at a time. If you try this with mbuna the new arrival will always be killed. So you want to add all the fish at once. This means that you should have the tank set up with an already mature external bacterial filter or a growing plant filter. You can mature an external bacterial filter easily by hooking it to another running aquarium for a few months, or else hook it to a water container to which a small amount (5mg/L) of ammonia chloride is added weekly for six weeks.

Now, with filter, plants, and rocks in place, its time to get some fish.

Since you are adding all the fish at once, it is best, both financially and for the fish, to purchase only subadult fish. All the fish should be roughly the same size at purchase, but do not choose only the biggest fish from a tank full of youngsters. If you do so you’ll end up with only males. Instead, select your fish more or less at random (rejecting any obviously stunted or sick fish of course). A swift scoop with a large net through a school of 2cm fry does the job nicely.

Most of the regularly available mbuna grow to the 10cm to 15cm length range, although most Petrotilapia species are a bit bigger, and some Labidochromis are a bit smaller. You don’t have to worry about matching species’ adult sizes when you go to select your fish. Instead, you have to match temperaments and keep aggressive fish away from the relative wimps. Below are several lists of compatible mixes composed of readily available species. For all the suggested species mixes, 1 fish for every 10 liters of tank capacity is a good stocking rate, with 200 liters (20 fish) being the minimum tank size. You want roughly equal numbers of individuals for all species, with six being the minimum suggested number of individuals of any one species for any given tank. Since you are buying subadults, you will not be able to sex them, so be prepared to remove (or lose) some males as they mature.

Other hints at keeping deaths to a minimum are more subtle. Avoid putting together fish with similarly colored males. Not only does a uniform color scheme result in a rather boring display, it also results in cross breeding and a lot of inter-species aggression. Also, for the same reasons, do not put together closely related fish species or fish of the same species but of different color morphs.

You should be aware that even with lots of caves and crowded conditions, some exceptionally aggressive mbuna, like Melanochromis auratus, are difficult to keep together at all. Henry and Jennifer Wilkinson (The Calquarium, June 1998) have had success raising these fish in a tank filled with clear plastic filter boxes, but all I’ve ever seen from them (in a more conventional mbuna tank) is unrestrained warfare (see sidebar). I would therefore recommend leaving these fish (and all large Melanochromis) out of your community aquarium, despite their brilliant colors. Happily, however, Melanochromis’ mayhem is directed mostly to their own congeners, so if you do include them your other fish have a reasonable chance of surviving well after the Melanochromis population is reduced to a single male.

One of the great conveniences of mbuna is their willingness to breed. In fact, you won’t be able to stop them. Breeding in mbuna is a casual affair, and there is no pair formation or bonding between the prospective parents. Instead the dominant male will quiver in front of the female, who (if receptive) will lay her eggs on a flat surface and quickly pick them up in her mouth. The fertilization of the eggs occurs when the female turns to mouth the male’s genital papilla. Ideally, after that the mothers should be removed to a safe secluded aquarium of their own. However, they are impossible to catch without tearing down the entire tank. Because of the weight of all the rocks in your display, you’ll get tired of this procedure pretty quickly. But do not fear, because mbuna are truly pathetic predators, with the exception of the larger, "long-snouted" Melanochromis species like M. chipokae. If none of these fish are present (and they are so aggressive you probably don’t want them anyway), any babies produced can and will grow up in the display tank with very few losses…just supply them with suitably sized food. The mother, however, eats very little (if at all) for the three to four weeks of incubation, and so she will be underweight and vulnerable during and after her time with the fry. Most deaths of females are the result of loss of condition from maternal duties. This is all the more reason to have a large, long tank with plenty of hiding places.

Mbuna need a lot of vegetable matter in their diet (with the exception of Labidochromis) and should be fed Spirulina flakes and blanched zucchini slices. Green peas and romaine lettuce are also good supplements, and yellow squash will help bring out their red and yellow colors. The last three may be less than enthusiastically received however. Failure to provide adequate roughage in the diet eventually results in intestinal problems followed by a usually fatal bacterial infection ("Malawi bloat"). In addition, the usual aquarium fare should be provided, but avoid rich and fatty foods like black worms.

The mbuna, except for Labidochromis and the aforementioned predatory Melanochromis species, will also graze on algae. This is good, since a lush algae crop will inevitably grow in any properly lit and stocked mbuna tank. The Labeotropheus species are the most enthusiastic algae eaters. But not even Labeotropheus will polish the glass clean like any self-respecting pleco would do, so your aquarium glass will need regular cleaning. The rocks will (and should) also become coated with bright green hair. But if you aren’t put off by the geographical inaccuracy, feel free to put a few bristle-noses (the South American Ancistrus sp.) into the tank for algae control. If you are a purist this mixing of continents may not appeal to you, but if so you should also be aware that almost every mbuna community aquarium (including the suggested ones given below) are mixtures of fishes that would never encounter each other in nature. Very few mbuna color morphs (or even species) are found beyond one isolated reef, island, or stretch of shore…and unless you know the exact location of your fishes’ range, it would be impossible to create a truly natural community anyway.

Algae growth on the plants is also inevitable, but established Vallisneria plants are so fast growing that this is mostly just an aesthetic problem. Thinning out older, algae covered leaves regularly will help, as will snails.

So what fish should you get?

Here are some nice groupings of readily available fishes that will give you a lot of color variety, aren’t likely to crossbreed, and are reasonably compatible:

1) A highly aggressive community (the loss of all but one male of each species and at least some females is likely: avoid this selection unless you are very brave)

Melanochromis auratus: yellow and dark-brown females, and dark-brown and silver-blue males. Or Melanochromis chipokae: black and electric-blue males, whitish and dark-brown females. M. chipokae is one of the predatory species, with M. melanopterus.

Pseudotropheus elongatus: deep blue and black barred males and brownish females. May be confused with Pseudotropheus minutus, a similarly shaped and colored, but smaller and much less aggressive, fish.

Pseudotropheus crabro: a yellow to golden-brown fish with dark brown vertical bars ("bumble bee").

2) A moderately aggressive community (some fish may still be lost):

Labeotropheus trewavasse: an indigo-blue fish with an orange dorsal (although other color morphs also exist).

Red zebras (Pseudotropheus estherae): a yellow-orange to orange-red fish.

Pseudotropheus minutus: deep blue and black barred males and brownish females. Do not confuse with Pseudotropheus elongatus, a similarly elongated and colored fish, but one that’s larger and much more aggressive.

Melanochromis johannii: black and electric-blue males, pale yellow females.

3) Another moderately aggressive community, (some fish may still be lost):

BB zebra (Pseudotropheus zebra): a stunning "black barred" and blue fish.

Pseudotropheus socolofi: a sky blue fish.

kenyi (Pseudotropheus lombardoi): a fish with blue and silver females, and orange males.

Labeotropheus fuelleborni "OB": an "orange-blotched" fish with an orangish background and black, blue, and white spangles ("calico").

4) A less aggressive community (no losses of fish are expected):

Labidochromis caeruleus: Colors range from spectacular solid yellow, through white, to black bars on a blue background. However, it is likely that these color morphs actually represent separate undescribed species.

Iodotropheus sprengerae: this fish is variable in color (most are quite plain) but nice ones have a yellowish-brown background and mauve sides (and are the only predominantly mauve aquarium fish available).

Cynotilapia afra: a blue and black barred fish with a yellow-orange dorsal fin (although other color morphs also exist).

Other commonly seen fish that can be considered for the moderately or less-aggressive communities are Pseudotropheus saluosi and Pseudotropheus "acei". P. saluosi is a very colorful smallish mbuna with blue and black males and orange-yellow females. They will however interbreed readily with Labidochromis caeruleus and other small Pseudotropheus, and possibly smaller Pseudotropheus and Cynotilapia species also. They should be considered a substitution for these fishes rather than a tank-mate. Pseudotropheus "acei" is a steel-blue fish with yellow fins. It is especially easily bred (even for an mbuna) but in all probability it has similar proclivities when it comes to cross breeding as does saluosi.

The non-mbuna cichlid species that will go well with both the moderately and less-aggressive communities include Cyrtocara moorii. This is a lovely sky blue fish with an interesting bulbous head. Also suitable is Sciaenochromis fryeri (the "electric blue hap"). In addition, almost all of the utaka (Copadichromis and related genera) or the peacocks (Aulonocara and related genera) can be kept with the fishes in the less-aggressive community, but I wouldn’t include these gentler fishes with any of the other communities. Also, these non-mbuna fish (especially Sciaenochromis fryeri) are much better fry predators than are the mbuna, and so they should not be included if you want your fish to successfully reproduce in the show tank.

So that should help you set up a fabulous mbuna display tank. Their constant breeding, territorial squabbling, and enthusiastic feeding, along with their undeniably spectacular color, surely makes an mbuna community the most entertaining tank you can own. Have fun!?

Melanochromis auratus colors

Subadult male and female Melanochromis auratus are yellow fish with two horizontal dark brown stripes that go down the length of the upper half of their sides. When the males mature, however, their body color below the lower stripe darkens to the same color as the stripe, turning a light fish with dark stripes into a dark fish with a light stripe. This process takes a couple of weeks to a month and occurs when the fish is about eight months old, unless the change is suppressed by the bullying of a more dominant fish.

The first time I witnessed this transformation was in my first mbuna community aquarium. This tank was a 200 liter aquarium that was nearly filled with limestone rocks and Vallisneria planted in clay flowerpots. It started out with six young Melanochromis auratus, six Pseudotropheus socolofi, and six red zebras (Pseudotropheus estherae).

Soon after the male auratus changed color he decided that he would fight the tanks’ dominant male Pseudotropheus socolofi for ultimate control of the tank. The socolofi then proceeded to thrash him. Fortunately I was able to rescue the auratus male before he was killed, and nursed him back to health in a separate tank.

Two months later, with fins and scales back in place, the auratus male was returned to the community aquarium. To my surprise the male, by then in full adult color, reversed his color-pattern again! He changed back into the brown-on-yellow female color over the next week as he hid from the male socolofi. Several months later, however, he changed color a third time (this time for good) when he went back to the male pattern. He never challenged the socolofi male again, but over the next year killed all five of the tank’s auratus females, making him the nastiest fish I’ve ever owned.

Other aquarium clubs and non-profit organizations can use this, or other articles, in their own journals or web sites, provided that credit is given to the author, the Calgary Aquarium Society, and The Calquarium. In the case of a reprint in a hardcopy publication, two copies of the published work are sent to the Calgary Aquarium Society at its mailing address. And in the case of a reprint in an Internet publication, a link back to the original article site must be provided in a prominent location.