Haitian cichlid

The Haitian cichlid — the 'black nasty' to people who keep it — is the only cichlid native to Hispaniola, the island shared by Haiti and the Dominican Republic. Isolated there for millions of years, it turns up across an unusually wide range of habitats, from mountain streams and lakes to brackish coastal lagoons. Wild fish reach about 21.5 cm; in aquaria, well-fed males grow noticeably larger and develop a heavy nuchal hump.

The name is earned. This is one of the most aggressive freshwater fish in the hobby, and it will kill tankmates two or three times its size. In practice it is kept as a solitary wet pet; a bonded pair is only realistic in a very large, heavily broken-up tank, and an ordinary community is out of the question. Plan on at least a 400 litre tank for one fish, with strong filtration, a sand or fine-gravel floor and rockwork that breaks up the sightlines.

Water should be hard and alkaline, 24–27 °C, pH 7.0–8.0, and kept stable — sudden swings can trigger bloat. Diet matters more than people expect: this is really an omnivore that leans herbivorous, feeding in the wild on algae, plants and snails, so the staple should be spirulina-based rather than a rich carnivore food. Too much protein is the usual cause of bloat. It spawns readily on a cleaned flat surface, laying 150 to 200 eggs that hatch in three to four days, with both parents guarding the young.