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Mbuna, the Lake Malawi rock-dwelling cichlids.
Mbuna; true, freshwater “reef” fishes.
The rock-dwelling cichlids of Lake Malawi are most commonly known by the native African name of “mbuna” (pronounced UM-BOON-UH). These are highly colored fishes which live in relative dense communities among the inshore rock reefs of the lake. All of the mbuna are maternal mouthbrooders (the females carry the fertilized eggs in their mouths until the fry are able to fend fore themselves) and the males practice an extreme form of polygamy.
In nature there are many different color forms (called “color morphs”) of some species. The relatively common Pseudotropheus zebra exists in its “normal” blue-with-black-bars, or “BB”, form (thus the specific name “zebra”) and as an orange-blotched, “OB”, form, a red-dorsal, “RT” form and many more. Some of these morphs are now recognized as true, separate species. For instance, the red zebra is now know to be Pseudotropheus estherae; the cobalt blue zebra is P. callainos (the “P.” is the abbreviation for “Pseudotropheus” and is often used when writing about more than one species all belonging to the same genus). A note on the scientific names of the Pseudotropheus genus is in order here; there is a great controversy about whether or not the name should be applied to the zebra and its allies. Two possible replacement generic names, Maylandia and Metriclima, have been proposed with the latter most likely to be the accepted name.
Besides rock-dwelling, what else distinguishes the mbuna?
Due to the fact that the mbuna are entirely rock-dwelling fishes it is safe to assume that they make their livings totally in and among the rock reefs. A good portion of the species of mbuna are rock scrapers. That is they scrape at and consume the algae covering on the rocks. The shape and placement of a given species’ teeth and lips often is a clue as exactly how it feeds. The algae-scraping cichlids have longer intestinal tracts which allow them to derive the maximum nutritional value from a food source which is relatively nutritionally poor. Interestingly, the first scientists to collect and export young mbuna from Lake Malawi to aquarium hobbyists were later surprised to find that the fishes’ head and mouth shapes often changed, after several months in aquariums, to such an extent as to be almost unrecognizable when compared to wild fishes. This was because the fishes were eating regular aquarium fare and were no longer banging their mouths against the rocks to scrape off the algae.
Other mbuna are invertebrate pickers and make their livings eating the worms, snails and insect larvae found living on the rocks. Other mbuna species evolved colors and markings similar to more commonly found algae-scraping mbuna so that they could mingle in with the other species and steal their fry (often directly from the brooding females’ mouths) or, with some species, scrape scales from the flanks of the other species. The fry-eating fishes are called pedophages and the scale-eating ones are called lepidophages. Needless to say these specialized feeders are not welcome additions to an mbuna rock-reef aquarium community.
How about spawning the mbuna?
Spawning the mbuna is almost as easy as falling off a log! The males are always setting up and defending territories in and among the rocks and can be seen to dig pits in the gravel at the base of the rock piles. Into these pits they entice any willing female of their species. They also do a good job of driving off any other males who may covet the gravel pits and associated territory. In relatively dense mbuna communities the males will usually stay fairly close to their territories and harassed females, or other males, can usually find a place to hide in among the rocks.
The actual spawning act is quite interesting. The male patrols his gravel pit or rock cave, turns on his best colors and spreads his fins to advertise to potential mates and to warn potential rivals. Any female who is ready to spawn will almost always find the male’s displaying to be irresistible and will eventually enter his territory.
There will be a frenzy of head-to-tail nipping, body slapping and chasing, and eventually the female will release one or two fairly large eggs into the gravel pit. She will immediately turn around and pick up the eggs in her mouth. The male will vibrate his body and spread his anal fin to best display his “egg dummies” or “egg spots”. These spots on the males’ fins are very nearly the same size, color and shape as the eggs the female deposits. This action causes the female to nip that the egg spots on the male’s anal fin. This nipping causes the male to release sperm into the pit which is pulled into the female’s mouth where the just laid eggs are fertilized. This spawning dance continues until the female has a mouthful of fertilized eggs; she then flees the pit and goes off the incubate the eggs.
The eggs hatch in about a week, but the female continues to brood the fry in her mouth. She will do this until the fry become capable of fending for themselves. At that point she will no longer let them swim back into her mouth and she will abandon them. The incubation period can be as long a 30 days; during this time the female rarely, if ever, eats. Generally, it is a good idea to remove brooding females to a separate isolation tank until she has released her fry and has been conditioned to the point that she can be placed back into the mbuna community tank.
What are the general water requirements for keeping mbuna?
Lake Malawi is a hard water lake with a moderately high pH. While it probably isn’t as important that the hardness be kept high it is important that the pH be kept above 7.0, and generally no lower than 7.2. Maintaining a pH above 7.0 can often be a problem in a freshwater aquarium. To do this mix crushed, hen-grade oyster shell, at a rate of 1 to 9, by weight, with the regular gravel. Be sure to test the pH and the alkalinity and do water changes when the alkalinity starts to decline and before the pH drops below the target value.
Lake Malawi is not a salt water lake so adding table salt or sea salt the aquarium water will do little to make the environment more comfortable for the mbuna. There are mixes made for the Rift Lake cichlids, but we at EECHO have not evaluated these products and have found that the mbuna in our hatchery do extremely well at a pH of 7.5, a hardness of between 180 and 250 mg/L as CaCO3, an alkalinity of 65 mg/L as CaCO3 and a temperature of 70-85º F.
Use all three kinds of filtration: mechanical, chemical and biological. Given that the pH is relatively high it is important that the biological filtration be properly maintained. An undergravel filter (with plastic egg-crating laid over the filter plate before the gravel is put in) works very well and requires little maintenance (siphoning the gravel is almost never needed with a properly setup undergravel filter).
Feed the mbuna an algae-rich diet and avoid high-protein feeds. Occasional feeding with frozen brine shrimp is okay, but should not be the staple diet for these fishes. A flake, tablet or pellet food made from Spirulina is especially good for mbuna. It promotes their natural color and helps prevent intestinal blockages.
One must keep closely related mbuna from hybridizing in aquariums. This happens easily, and such hybrids are of no value in the aquarium trade. When buying mbuna be sure that you are getting genetically pure fish and avoid hybrids.
If there are any questions please call us at 816/842-5936.
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