TROPICAL FISH ORIGINS: PART 3 – AFRICA

by Tom Sarac

The continent of Africa is home to many very popular aquarium fish, especially those commonly known as African cichlids. In particular, two major African rift lakes, Malawi and Tanganyika, together contain over 1,000 species of cichlids. The physical dimensions of these two enormous lakes are impressive, ranking them high among the deepest and largest lakes in the world. Lake Tanganyika covers an area of approximately 32,900 km2 (12,702 sq mi). Lake Malawi covers an area of approximately 31,000 km2 (11,969 sq mi).

Average surface temperatures vary between approx. 23 and 28°C (73 and 82°F) as dictated by the season. The factors that influence water transparency in both lakes are those of rainfall (seasonal), substrate, algae blooms, and wind.

Lake Victoria, which is another of the Great African Lakes, is home to numerous fascinating cichlids, but it has suffered greatly from severe human population pressures as well as other factors. The result is that many of the endemic species are rapidly becoming extinct. The availability of wild fish from this lake is limited.

West and Central Africa are home to a variety of popular aquarium fish. Unfortunately, many interesting species are not frequently seen in retail stores with regularity. The ever popular and graceful Congo Tetra (Phenacogrammus interruptus) is an exception, and commonly seen in aquariums around the world.

TYPICAL HABITAT STRUCTURE

The land areas surrounding the huge Tanganyika and Malawi lakes have similarities. Their shorelines are generally composed of rocks, scattered with intermittent sandy beaches and bays.

Isolated rocky outcrops and islands often have specific communities of fish species found only in that particular location, which is a key factor in the formation of distinct species of fish in these lakes. The rock grazers of the genera Tropheus and Petrochromis are frequently found around the base of tall, rocky structures and islands in Lake Tanganyika. The same can be said for the mbuna (rock-grazing cichlids) of Lake Malawi. The boulders and rocks provide many species with algae, an important source of food. The algae also serves as refuge for small organisms (insect larvae, crustaceans, etc.), providing an additional nutrition source for fish.

The underwater habitats of interest are generally composed of rocky boulders, transitional rocky and open sandy areas. There are also shallow muddy bays that are not as densely populated with fish.

The West and Central Africa river-type habitat is composed principally of sand or gravel with root-type driftwood and smooth rocks. Rapids and pools of water typically found in larger rivers provide a variety of environments. Fish species in these environments enjoy well oxygenated water of a low to medium hardness and close to neutral pH.

To complete the picture, we suggest anyone keeping African cichlids confirm the water chemistry required for these hard water loving fish, based on the lake they evolved in. Lake Tanganyika contains water that is significantly harder than either Malawi or Victoria. The dietary requirement of fish can vary considerably as well, thus be careful when mixing various types of African cichlids together. Some types of Tanganyikans are not to be kept with some of the cichlid species found in lakes Victoria or Malawi due to dietary incompatibility.

African aquatic habitats are without a doubt home to some very interesting species of cichlids and other fish that have contributed to aquarium keeping and enjoyment. Providing African cichlids with ideal water conditions is not difficult since increasing pH and water hardness is an easy and controllable process. To sum up this third installment on tropical fish origins, we can conclude that Africa has brought us many easy to care for and appreciated species of fish, and keeping them is an experience that should and will be cherished.