Mbuna of Lake Malawi
by Nimrod Orenstein (Ssssssspit_Fire)
Lake Malawi is very unique due to all the different species that can be found in its waters. More than 900 species have already been discovered. One of the things that makes this lake so unique is the way these cichlids feed. Thanks to their incredible feeding specialization; many diverse species have evolved in this lake and no where else. In this article I will look at the different aspects in behavior and feeding, both in the wild and in captivity.
The breeding method which characterizes all the cichlids in the lake (except Tilapia rendali which is a substrate spawner) is very distinctive. The cichlids of the lake are maternal mouth brooders and the spawns occur in a fascinating way; mostly by the egg dummies method.
The egg dummies are spots on the anal fin of the males (and sometimes females). The function of these egg dummies is to fertilize the eggs in the female's mouth in a very simple way. After an egg or two were dropped, the female collects the eggs into her mouth, then, the male shows the female those egg dummies. The female thinks it's a real egg and tries to collect it while the male releases it's sperm and fertilizes the eggs.
The Mbuna group of cichlids live mostly in and around rocky habitats. They stay close to the rocks in order to supervise their territory and females. The word Mbuna, which means 'rock dwellers', comes from the language spoken in northern part of the lake, Chi Tumbuku. These fish can be found in depths between 0-40 meters, sometimes Mbuna can be observed at lower depths, but that's not very common.
The Mbuna feed from different sources of food, some herbivore, some omnivore and some are carnivores and piscivores. There are several algae eating methods that I will explain in this article. The herbivorous cichlids on the lake (that most of them are included in the Mbuna group) are characterized by long intestines. Since algae is a low calorie food, long intestines help the fish exert less energy during digestion. The herbivorous species needs to collect food all day long in order to be satisfied, while the predators can go for a hunt several times a day and could lay back for the rest of the day.
There are few differences between Cynotilapia species and Pseudotropheus species. Cynotilapia have wider teeth in the outer jaw. The Latin meaning of Cynotilapia is "Dog Tilapia". Cynotilapias are mostly observed in the deeper parts of the lake. The strange thing about the Cynotilapia species is that have big threatening teeth but don't scrape algae or catch prey; they use them to catch Plankton hovering in the water.
An interesting member of this species is Cynotilapia pulpican. It was recently reclassified from Pseudotropheus sp. "kingsizei". This fish is named after a small but energetic diver who worked for one of the exporters in the lake. The pulpican is endemic to the coasts between Maingano and Likoma islands. In spite of its BIG name it only grows to 3 inches long in the wild, the fish was discovered in 2002.
One of the remarkable fish in this genus is Genyochromis mento. A remarkably aggressive Mbuna that eats the scales and fins of other fish. This fish is a wolf in sheep's clothing. Like Plecodus straeleni from Lake Tanganyika, G. mento disguises itself as other Mbuna in its area in order to get close to them. Once in range, it quickly bites off a fin or a scale using its teeth that were designed specifically for this purpose. This eating specialization has no negative long-term effect on its prey as their scales fins will grow back. This fish is not marketed in the hobby due to its extreme aggression.
Iodotropheus is a genus containing only 3 species. Some decades ago they were thought as a single species genus. Researchers believe Iodotropheus is an ancient genus. Iodotropheus sprengerae (Rusty cichlid) can be found in southern part of the lake and has a small distribution, limited to 3 islands. As mentioned before, Iodotropheus is an ancient genus that survived only in places that have a low population of locals. The small distribution of I. sprengerae indicates it had larger distribution in older times. In the 70's this fish was named Melanochromis brevis, Later on it got the name Rusty. The Rusty is one of the first cichlids to be exported out of the lake. The Rusty is one of the gentlest Mbuna in the lake. This fish does not dig, does not hurt plants and is not territorial. It has similar to some Labidochromis species not only in terms of aggressiveness but males and females are also monomorphic.
Another species of Iodotropheus is I. stuartgranti. This discovery astonished the researches because until that time they thought Iodotropheus was a single species genus. As the Rusty, I. stuartgranti also reminds some species of Labidochromis. Territorial males were not observed.
Labeotropheus (i.e. L. fuelleborni or L. trewavasae) are typical herbivores. Their jaw is very specialized for feeding. They have cartilage that is directing downwards so they could graze algae from rocks. Their mouth structure is very similar to the mouth structure of the Tropheus from Lake Tanganyika.
The Labeotropheus teeth are located very close to each other so algae grazing is performed like a nail file. The grazing is so extreme; you can see teeth marks on the rock after the fish grazed the algae off.
Most of the Labidochromis species are insectivores (insect eaters). They are generally characterized by light colors and low aggression. Their stomach contents are filled with the remains of dozens of snail bodies. Some Melanochromis species used to belong to the Labidochromis genus, the most common one was Melanochromis joanjohnsonae which is found in the upper 4 meters of the rocky habitat in the lake and is endemic to Likoma Island.
Fish from this genus are often found in the rocky areas of Lake Malawi. They are characterized by a big and wide pharyngeal jaw, and an elongated and striped body. A lot of fish in this genus do not have any specific "diet definitions". Some have a varied diet like Melanochromis melanopterus which feed on aufwuchs and also eat other Mbuna's fry. The largest Melanochromis individuals observed in the wild about 5 inches long, while in captivity can grow to 7+ inches.
There is a big argument whether calling these fish Metriaclima or Maylandia, I'm not getting into the bottom of this argument though I think these fish should be called Metriaclima. All Metriaclima used to belong to the genus Pseudotropheus but have been reclassified. Some fish, like M. greshakei and M. lombardoi are algae scrapers. While M. estherae (Red Zebra) prefer eating invertebrates.
Another interesting species is M. livingstonii, once know as M. lanisticola, is a Malawi shell dweller! Normally its maximum size is 2.5 inches but in the southern part of the lake it can grow up to 5 inches long. In this size, it can no longer enter shells. This fish can also be found in Lake Malombe. This fish IS a maternal mouth brooder but at the end of the holding period the small fry are transferred into the small Lanisticol shell. The holding period of this fish is very short comparing to other Malawi cichlids (16 days at maximum), most likely because the small fry are transferred to the shells and not "spat out" to the big lake like other Malawi cichlids.
The Petrotilapia are giant Mbuna (biggest in the lake) that obtain magnificent colors in complete maturity. Petrotilapia contains several species and dozens of geographical variations. Since Petrotilapia are herbivorous, they need large quantities of algae. Their mouth and teeth structure is built in such a way that even when the mouth is closed, the fish's teeth still stick out. Petrotilapia have such a "frightening" teeth structure that when grazing, the algae is completely removed from the rocks. Their teeth are also very flexible. The mouth structure of the Petrotilapia is very similar to those of Lake Tanganyika's Petrochromis.
Mostly herbivorous with some exceptions. Pseudotropheus is my favorite Mbuna genus. A very interesting and popular fish is Pseudotropheus demasoni. P. demasoni is endemic to Pombo Rocks and Ndumbi Rocks and also south of the Ruhuhu River. P. demasoni is usually found in the upper 4 meters of the rocky habitat in Lake Malawi. Large fish often ignore P. demasoni due to its small size. In the wild some, this fish has a mild temperament but in captivity, very aggressive toward others of its own species. P. demasoni is very smart in selecting its eating sites so it will have no competition for food.
Another cichlid I would like to refer to is the Pseudotropheus crabro (hornet or bumble bee cichlid), its feeding method and co-living is amazing. P. crabro used to belong to the genus Melanochromis. P. crabro feeds on parasites that are living on other fish. The crabro co-exist in big caves with a large catfish known as Kampango (Bagrus meridionalis). The crabro feeds on the parasites Argulus africanus that is a type of fish louse. The parasite attaches itself on the Kampango's skin and the crabro uses its teeth the scrape the parasite off. Sometimes the crabro sees a diver in a black diving suit, and thinking it's a fish, tries to scrape parasites off the suit. During the Kampango's spawns (thousands of eggs) the crabro enjoys caviar meals. The crabro is well known for its ability to change color very quickly from light yellow to black. While the Kampango is spawning, the crabro slowly approaches and steals eggs. I one crabro's stomach 1068 Kampango eggs were found. The crabro and the Kampango have a weird relationship; day time the crabro cleans the Kampango from parasites and at night steals its eggs.
Tropheops species are usually very aggressive. These fish can be found in the habitats along the North West side of Lake Malawi between the areas of Kirondo and Kande. Tropheops only scrape the upper part of the algae by grabbing the algae in its mouth and twisting their body to rip it off. Tropheops, like Metriaclima, is a very diverse genus that includes dozens of geographical variations.
Mbunas in the aquarium:
Mbunas in the wild are very aggressive should be kept in large aquariums with many rocks for territories. Depending on the species, minimum tank sizes begin at 30 gallons and go up to 75 gallons. Picking the right size of aquarium is very important. These fish require a temperature of 72-78 degrees F. and a pH of 7.8-8.6. Please notice, not all Mbuna can be populated together in the same aquarium! Mbunas had proven themselves to be very easy to breed in the aquarium, as the long as the water conditions are good and the fish are mature enough.