Simochromis diagramma Breeding Guide

How to breed Simochromis diagramma, a Lake Tanganyika algae-grazing cichlid that is an aggressive maternal mouthbrooder best bred in a colony.

Overview

Simochromis diagramma is an algae-grazing cichlid endemic to Lake Tanganyika and is the largest species in its genus, reaching about 19.5 cm TL. It prefers murky waters with rock-rubble substrates, usually shallower than 5 metres (16 ft) and never deeper than about 10 metres (33 ft). The species is listed as Least Concern by the IUCN and is also found in the aquarium trade. It is a maternal mouthbrooder in which the female broods the eggs and larvae in her mouth; reported brooding females measure roughly 6.0 to 9.0 cm SL and incubate larvae up to about 1.56 cm.

Conditioning

The species follows a vegetarian diet, with FishBase placing it at a low trophic level of 2.0. Conditioning should therefore centre on a high-vegetable, algae-based diet rather than rich protein foods, mirroring its natural grazing ecology and reducing digestive problems common in herbivorous Tanganyikan cichlids.

Breeding Setup

This is an aggressive species, so colony husbandry with multiple females and ample broken-up rock structure is advisable to diffuse male aggression. Hard, alkaline Tanganyikan water suits it; FishBase cites a temperature from around 25 degrees C upward for the species' range. Sand substrate and rocky cover replicate the shallow rubble zone it inhabits.

Spawning Behavior & Trigger

As a maternal mouthbrooder, the female takes the fertilised eggs into her mouth after spawning and incubates both eggs and larvae there. Spawning typically occurs in the shallow rocky zone the species favours, with the female carrying the developing brood while remaining able to forage and shelter.

Egg & Fry Care

The female mouthbroods the larvae until they reach a total length of roughly 1.56 cm, after which the free-swimming young are released. A holding female may be separated to protect the brood and allow undisturbed release. Released fry can be offered finely crushed vegetable-based foods and small live or frozen items suited to their size.

Common Challenges

Aggression is the principal difficulty: a single male can severely harass females and rivals, so a colony with plenty of cover is preferred over a single pair. A protein-heavy diet is inappropriate for this herbivore and can cause digestive issues. Holding females may abort a brood under stress.