Kenya

The crazy fish, Butis butis, is a flathead gudgeon of coastal and brackish waters across the Indo-Pacific, from eastern Africa to Fiji. The most commonly traded member of the genus, it has many other names, including crocodile fish, duckbill sleeper and upside-down sleeper. A nocturnal ambush predator, it often swims upside-down, and it is territorial and not sociable with conspecifics, so is best kept singly.

The widehead catfish, Clarotes laticeps, is a large predatory catfish recorded across much of Africa, from Senegal and Guinea east to Egypt and Kenya. It inhabits large lakes and rivers and grows to 80 cm, though it is unlikely to reach this in captivity. Uncommon in the trade, it is capable of swallowing surprisingly large prey and is unsuitable for all but the biggest aquaria.

Pundamilia nyererei is a maternally mouthbrooding cichlid endemic to Lake Victoria, recorded only from the southern part of the lake in Tanzania. It is mostly restricted to rocky, littoral habitats around islands. At least 11 populations are known and male colour varies with locality, so fish are labelled with collection details to avoid hybridisation in aquaria. Males are aggressive and can kill other males if the tank lacks cover.

The grass carp, Ctenopharyngodon idella, is a large cyprinid native to the Amur River system in eastern Russia and northeastern China. Adults typically reach 800 to 1200 mm, making it a wholly unsuitable aquarium subject, though an albino form is traded. Widely introduced for aquaculture and weed control, it has caused serious damage to natural waters, and unwanted fish should never be released.

The soda cichlid, Alcolapia alcalica, is endemic to Lake Natron in Tanzania, a shallow soda lake full of hot, alkaline springs. The lake runs at pH 9.5-10.5 and 32-43.5 °C, and though captive fish can be acclimatised to more normal conditions, this must happen slowly, with the pH kept above 8.0 and the temperature at 28 °C or more. Exceptionally rare in the hobby, it excretes urea where most fish excrete ammonia, and periodically gulps air at the surface.

Graham's soda cichlid, Alcolapia grahami, is endemic to Lake Magadi in Kenya, a shallow soda lake full of hot, alkaline springs. It lives around the spring inlets and lagoons of the shoreline in water of pH 9.5-10.5 at 32-43.5 °C, and excretes urea where most fish excrete ammonia. Exceptionally rare in the hobby, it can be acclimatised slowly to more normal conditions, but the pH should not drop below 8.0 or the temperature below 28 °C.