The Convict cichlid (scientific: Amatitlania nigrofasciata), known also as zebra fish, is a cichlid species native to the coasts of Central America, encountered in both the eastern side of the continent from Guatemala to Costa Rica and the western part, from Honduras to Panama. It usually prefers streams with moderate current and finds shelter in rocky areas, especially in the various cracks created by this type of substrate, and can tolerate water of lower temperatures, allowing it to inhabit lakes in higher latitudes. The species has a grey-blue body with a characteristic pattern of 8-9 vertical stripes and a greenish finish at the end of its fins. Males are usually larger, with pointed fins while females have more intense colours, which is unusual for fish species. It is considered a small fish, as it can reach around 4 inches (10 cm) and it has a lifespan of around 10 years.
This species is one of the most famous and easier cichlids to keep in a successful aquarium. It requires a 20-30 gallon tank (75-120 L), filled with fine gravel or sand. A variety of rocks, pots and pieces of floating wood should be provided as the Convict cichlid is highly aggressive and will need plenty of hiding spots to avoid aggressiveness of fellow individuals. Moreover, it really enjoys burrowing, so aquatic plants should be avoided as they will eventually lose their roots.
Regarding water quality, the species requires an alkaline water, with a pH around 7-8 and water hardness between 10 and 15 dH. The convict is an omnivore that feeds on invertebrates, organic matter, plants and algae. Due to a modification of its jaw, which allows it to extend it, it can adapt to different kinds of food, making it very robust and tolerant to different environments.
Due to its extreme aggressiveness it is not recommended to add it to a community tank. While aquarists report that it can successfully be kept with species of the same size and aggressiveness, as it can stand up for itself and protect its territory against mighty cichlid species, it is recommended to keep it separately, especially during breeding seasons. Convicts can be so aggressive that they will not hesitate to even bite your fingers, thus special care should be given especially when cleaning the tank.
It reaches sexual maturity after only 4-6 months and has high levels of libido, making it one of the easiest species to breed. In their natural environment Convict cichlids are cave brooders, laying their eggs on vertical surfaces. In the aquarium, the male will chose a territory and try to seduce the female, with which it will establish an exclusive bond. After spawning and fertilizing, both parents guard the territory and fan the eggs, using their fins and tails in order to provide them with more oxygen. The eggs hatch within approximately 2-3 days and remain within the territory, enjoying the parental care for 4-6 weeks. During this period, parents help them to feed by moving plants and digging in the ground in order to find potential prey, while the procedure of fanning continues, especially during the night. Sometimes Convict cichlids might display extended parental care, and even adopt fries from other couples.
Due to the great diversity of colors and morphological characteristics among individuals, scientists had a great adventure trying to determine the taxonomy of the species, moving it from family to family during many years. However, its high tolerance and easy breeding have made it not only one of the most famous species for aquariums but also the most used freshwater fish species in research.
Froese, Rainer and Pauly, Daniel, eds. (2015). ” Amatitlania nigrofasciata” in FishBase. February 2015 version
Axelrod H.R. 1993. The Most Complete Colored Lexicon of Cichlids