Eggs laid by this method regularly ventilated for constant oxygen supply to ensure proper development. Also, the eggs are tightly guarded by their parents at all stages of development. There are three classifications in substrate brooding at Lake Tanganyika:
A) Classic substrate brooding– the eggs are laid and fertilized upon a flat stone, sediment, crevices or small caves. During the course of evolution, cichlids have developed a specific body shape suitable for the spawning site as a need for high predation pressure. There are cichlids that developed elongated and cylindrical body shape, for example, the cichlid – Neolamprologus leleupi (Poll, 1956). Males and females of this species live solitary. The female uses a small cave as a territory. When a wondering male encounters a ripe female ready to spawn, courtship takes place and spawning occurs in the female’s cave. After spawning, the female ventilates the eggs inside the cave while the male stays outside the cave and guards the eggs and the female. The male stays with the female until the juveniles leave the spawning site, few weeks after full development.
There are cichlids, which developed a high and flattened body shape, for example, the cichlid – Altolamprologus compressiceps (Boulenger, 1906) .Males and females of this species are not territorial except for breeding season. When a male and a female joins together, they are looking for a crack in rocks or along tree trunks, large enough for the female to squeeze into and lay eggs. After spawning, the male is clinging to the opening of the spawning site, releasing his sperm and fertilizes the eggs with help of the female’s fins flaps (thanks to that, contact occurs between the sperm cells to the laid eggs). Immediately after, the female ventilates the and guards the eggs by blocking the opening with the body. The male guards the female and the clutch outside the cave and stays with the female until the offspring leave the spawning site, only a few days after full development. Eggs development to fry takes 10 to 14 days, depending on the species.
B) Brooding in shells– a unique at it scale breeding tactic of cichlids in lake Tanganyika. Many shell-dwelling cichlid depends on shells for survival. Shells serves cichlids as a shelter from predators as well as to breed and produce offspring. Empty shells at the lake are scattered mostly at sandy areas away from the reef, thus the shell-dwelling cichlids are exposed to predation at any time. Spawning occurs in empty shell, mostly of the endemic snail Neothauma tanganyicense. In most of the shell-dwelling cichlids species, the female role is to ventilate the eggs inside the shell, while the male stays close to shell and guards the female and the clutch. After three weeks, the fry starts to pop out of the shell entrance in quest for food (zooplankton). The male and the female gurds the fry together at the territory for few more days( varies between species, up to two weeks).
Lamprologus callipterus (Boulenger, 1906) is a shell-dwelling cichlid that developed a unique morphological and behavioral adaptations. Harem reproduction – single male “owns” an half a meter diameter territory scattered with dozens empty shells. In this territory, there are dozens of adult females. The male’s total length is 15 cm which enables it to carry shells by mouth (often with females inside of them) from other males territory and increases his harem. If a male “stole” a shell that contains the offspring of another male, he will eat the offspring who do not carry his genes, before moving the shell to its territory. The impressive size also allows the male to defend his territory and fend off predators more easily. The maximum length of the female is 6 cm and its function is to ventilate the eggs and care for development. Due to it’s big size, the male cannot enter the shell and fertilize the eggs. Fertilization occurs when the male releases semen at the entrance of the shell while the female(located inside the shell) flaps fins and actually pushes the seed onto the eggs and fertilizes it.
C) Cooperative substrate brooding– a unique breeding tactic of cichlids in Lake Tanganyika and characterizes the “brichardi complex” cichlid group – eight different species with the same social behavior. There is one or more representative from this group at the rocky area along the lake shores, mainly at a depth of 7-15 meters. Male and female live together for long period of time and raises many generations of descendants. Older offspring help their parents guard the younger juveniles And forming a kind of “protective zone” around the territory and thus increases the survival of the fry. The bigger offspring scattered further away from the rocky territory and used as observers on the environment against predators. If predator attacks, these observers warn the rest of the colony, including the adult male and female. Usually, those who’ll be eaten are the observers (who is not sexually active) and thus low species vulnerability affects.