Tyrannochromis macrostoma was first described in 1922 by Regan in “The Cichlid Fishes of Lake Nyassa”, Proc. Zool. Soc. of London 1921 p. 719. The genus name Tyrannochromis was given in 1989 in the description of Eccles and Trewavas. The name can be broken into two parts. Tyranno comes from Tyrannus and means ‘tyrant’. The description does not explain why this name was chosen. Possibly it is a reference to the size of the species, the large mouth, the diet consisting of fish, and its strategy to outwit fish from an ambush. The second part ‘chromis’ is an ancient name that refers to the colourful cichlids, damsels and wrasses.
The species name macrostoma is derived from two ancient Greek words. Makros means ‘long or high’ and stoma means ‘mouth’. This is a reference to the very large beak of this species.
In the aquarium trade, this species is also referred to as “Haplochromis Black Belly”.
Tyrannochromis maculiceps, Tyrannochromis polyodon, Cyrtocara macrostoma and Haplochromis macrostoma.
Throughout Lake Malawi, the color of Tyrannochromis macrostoma is more or less the same. Previously, there were two other described species that differed only in form. At Chirwa Island there is a high-built variant (formerly Haplochromis maculiceps) and a very elongated variant (formerly Haplochromis polyodon). Both variants have been labeled synonymous in later descriptions.
With a maximum length of about 35 centimeters, Tyrannochromis macrostoma is a large fish. This only applies to males, by the way. The females remain a lot smaller at 24 centimeters. They have an elongated body that is highly compressed laterally. As can be seen in several piscivorous species, Tyrannochromis macrostoma also has a large head and a deeply incised mouth.
Young animals and females have a light grey-brown ground colour. A dark longitudinal band runs from the gill cover to the caudal peduncle. In the upper half of the body, two incomplete and interrupted dark longitudinal bands are still visible, as well as unclear transverse bands over the flanks. This pattern is very reminiscent of Protomelas taeniolatus specimens. Adult males in breeding color are brilliant blue with a pale yellow zone on the belly.
Color during the hunt
During the hunt, the abdomen of Tyrannochromis macrostoma becomes almost completely black. The young fish are very similar to Tyrannochromis nigriventer. As soon as they get a bit older, Tyrannochromis macrostoma can be recognized by the black belly.
Typically, the back of a fish is darker than the belly. As seen from above, the color of the back then disappears against the background. As seen from below, the light color disappears against the light of the sun. The dark belly may be a result of the hunting technique of Tyrannochromis macrostoma in which they attack the prey at a 45-degree angle and slightly tilted. They assume this position only after finding prey. The inverted color scheme can also be found in, for example, Synodontis nigriventris, the Upsidedown Catfish.
In adult specimens, the distinction is easy to determine by color.
Tyrannochromis macrostoma is endemic to Lake Malawi, where it has a large distribution area. One can safely say that it can be found all over the lake, without local color variations.
Tyrannochromis macrostoma is a notorious predator that mainly targets Mbuna in nature. It forages along the rocky coasts and regularly dives into burrows in search of prey. Mbunas up to 10 centimetres in size are not safe when an adult predator is nearby.
In the aquarium, it is best to offer them solid food: earthworms, shrimps, mussels, fish meat, and the like.
It goes without saying that a large fish like Tyrannochromis nigriventer gets a large aquarium. A 2-meter aquarium may be regarded as a minimum housing. In addition to a reasonable swimming space, it is also recommended to provide a rock formation with sufficiently large caves. Here the females can withdraw from the attention that the male has for the females. It is best to keep them as harem. The male must then divide his attention among several females.
Preferably use (filter) sand on the bottom. The male can dig a shallow nesting pit in this as soon as they are ready to reproduce.
The water may have a temperature of about 22 to 26 degrees Celsius. The pH may be a bit harder with a value of 7.5 to 8.5.
Breeding Tyrannochromis macrostoma
No special breeding aquarium is required for the reproduction of Tyrannochromis macrostoma. The spawn can simply take place in an aquarium with other species. It does take a long time before a male is fully mature and takes on the breeding colors.
As soon as the Tyrannochromis macrostoma male notices that a female is ready to spawn, he digs a shallow breeding pit. He prefers to do this under a rock. The color of the male changes to a brilliant blue with a yellow belly. The crater of Tyrannochromis macrostoma can be about 50 centimeters in diameter in the wild. By comparison, that of Tyrannochromis nigriventer is much larger at 100 centimeters.
The male tries to lure the female to the shallow pit. He swims in front of the female and flares his fins. The gills are also extended so that the male looks as imposing as possible.
When the female follows him to the spawning pit, they circle each other. The female lays some eggs that are fertilized by the male while circling. The female turns around and takes the eggs in her mouth. The male continues to retrieve the female until all the eggs have been laid. A large nest can contain up to 150 eggs. The man’s role is then played out.
Raising the fry
The female incubates the eggs in her mouth. The eggs hatch after a few days, but the young fish remain in her mouth for about three weeks after spawning. They live on their egg yolk sac during this time. Then they are released to search for food. However, the young Tyrannochromis nigriventer will return to the female’s mouth for some time if danger threatens. You can feed the fry with small live or frozen food, but they will also eat small granules or flakes.
John de Lange