General Article: Lake Malawi

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Introduction to Lake Malawi

by Greg Steeves

Lake Malawi is the ninth largest of the planet's lakes. Lake Malawi, like Lake Tanganyika is long and narrow, and very deep. The pH values in this lake are in the range of 7.7-8.6, which is slightly lower than Tanganyika and not nearly as varied as the measurements taken in Victoria. Most water saturation occurs at the surface here, as in Tanganyika. Deeper water levels in the lake are devoid of oxygen, thus fish life is restricted to the aquazone near the surface.

Most of the colorful fish familiar to hobbyists are found in rock pilings near the shore and in boulder reefs where predator evasion is easiest. These fish are called "mbuna", a word spoken by the people of the area that means 'rock fish'. Along with rocky outcroppings, Lake Malawi also has sandy stretches and grassy areas. Each biotope has it's own compliment of animals.

I categorize Malawian cichlids kept by aquarists into two broad groups. The first, the mbuna, are torpedo shaped and generally very fast (try netting one out of a large tank). These fish all appreciate a spacious tank full of rock work that form many crevices and caves. Dominant males will often stake one of these spaces out as theirs, and ward off all intruders. The exception to this would be a female of his species in spawning condition. In this case, the female might be allowed to enter his domain for the brief period of time during which the act of spawning takes place. When the female has finished laying her eggs, the males is usually still in the mood and chases her trying to entice her into more breeding. If she doesn't have a place to hide, his overzealous advances could prove harmful to her. Soon he will give up on her and go back to staking out his part of the world. Some of the fish in this catagory include Labidochromis, Pseudotropheus, and Melanochromis to name but a few.

The second group of fish most common from Malawi are the Haplochromis type species. These would include the popular Aulonocara, Nimbichromis, Copadichromis and Protomelus, and then some. These fish are very differently shaped from mbuna. Haplochromis-like fish have a higher body profile, longer flowing finnage, and are much more vertically compressed than mbuna. Female are usually very drab. The brilliant coloration is restricted to the males in these species. These fish may stray a little further into deeper water than mbuna but are usually found close to shore also. You can see clearly how these fish, being vertically compressed, might also find refuge in reedy and grassy areas. Haplochromines are also piscivores, whereas mbuna are, for the most part herbivores (aufwuchs-eaters). All cichlids that I know of from Lake Malawi are mouth brooders.

With a little caution many species can be mixed in a large tanks and the intense bright coloration of these fish make for a stunning display. Most Malawian cichlids do just fine on prepared flake, however spirulina flake is appreciated, and will help in avoiding Malawian bloat, a condition where a fish cannot properly process the food it eats. Malawian bloat is most common in mbuna, which have a very long instestinal tract specifically designed for processing plant matter. This tract becomes blocked and cannot digest properly. Good water quality and much vegetable matter in their diet will go a long way to keep this from happening.

In short, the many colorful creatures from Lake Malawi are truly fascinating to study and a real treat for the eye.

 





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