Convict cichlid

Water parameters

Tolerated range for this species. Aim for the middle of each band rather than the extremes.

Tank and habitat

Substrate: any.

Behavior

Plant interaction: destroys most plants.

Feeding

Opportunistic omnivore that eats almost any food offered. Standard pellet and flake foods, frozen bloodworm, frozen brine shrimp, frozen mysis, live food (where appropriate), algae wafers, and blanched vegetables are all readily accepted. Wild fish forage along the substrate and on rock surfaces, picking at biofilm, plant matter, insect larvae, small crustaceans, and detritus, so a varied diet matches their natural pattern. Two feedings a day is plenty. The species is famously easy to overfeed because adults beg at the glass whenever the keeper approaches the tank, and convicts will eat past satiety; portion size matters more than food type. Breeding-age fish on a varied diet show more intense coloration during spawning.

Compatibility

• Not a community fish despite its sale as one. A breeding pair attacks anything in the tank, often including fish substantially larger than itself
• Can work as a single specimen (one fish without a partner) in a community of medium-to-large fish, where territorial behaviour is much less intense
• If keeping a male and female together, assume they will breed. Plan tank size, tankmates, and offspring management upfront
• Suitable tankmates for a breeding pair require either size (large Central American cichlids: firemouth, jack dempsey, salvini, large barbs) or armour (bristlenose pleco) plus enough territory in a 200-litre or larger tank
• Avoid small, slow, or delicate species; convicts bully whatever they can dominate, and shrimp and small snails will be eaten
• The leucistic 'pink/white convict' variety behaves identically to the wild barred form; selective breeding for colour has not affected temperament

Origin and habitat

A small Central American cichlid (family Cichlidae, tribe Heroini). Günther described it in 1867 as Heros nigrofasciatus from specimens collected in Central America; the species has since been moved through several genus assignments, including Cichlasoma, Archocentrus, and Cryptoheros, before Schmitter-Soto's 2007 revision of Archocentrus (Zootaxa 1603:1-78) split that genus into multiple new genera and assigned the convict cichlid to a new genus, Amatitlania. The same paper described three additional new Amatitlania species (A. siquia, A. kanna, A. coatepeque), so many fish previously lumped under A. nigrofasciata in older literature may actually represent these closely related species; A. siquia in particular has a broad distribution that overlaps much of what was historically called A. nigrofasciata. A 2008 paper led by Říčan proposed merging all Cryptoheros and Amatitlania species into Hypsophrys, and a 2016 mtDNA study by Bagley et al. cast doubt on whether the genetic divergence is sufficient to support the 2007 split at all; the taxonomy remains unsettled. The genus name Amatitlania comes from Lake Amatitlan in Guatemala, and the species epithet nigrofasciata is Latin for 'black-striped', referring to the vertical bars on the flanks that also produced the English name 'convict' (a comparison to striped British prison uniforms). Under the current concept, A. nigrofasciata is native to northern Central America, broadly across Guatemala, Honduras, and El Salvador, with related species in the genus extending south to Costa Rica and Panama. Adults reach about 10 to 13 cm; males are slightly larger and more elongate than females, with longer fins, while females are smaller and develop an orange-gold belly patch when in breeding condition. A leucistic selective-bred strain (white/pink/gold convict) is common in the trade alongside the wild barred form. Wild habitat is the broad range of Central American freshwater: streams, rivers, lakes, and ponds, almost always with structure (rocks, sunken wood, undercut banks) rather than open water. The species is one of the most extensively studied non-avian models for monogamous pair-bond and biparental-care behavior, with peer-reviewed work covering serial monogamy, parental sex-role division, mate recognition, and pair-bond stability (Snekser and Itzkowitz 2019 PeerJ; Snekser et al. 2011 and later; Wisenden 1994 and 1995). IUCN status is Data Deficient (New Mexico BioPark Society 2019 assessment). Released or escaped aquarium fish are established as an invasive species across much of the warm world: in the US they have self-sustaining populations in California, Arizona, Louisiana, Idaho, Wyoming, Nevada, Hawaii, and Puerto Rico, often confined to thermal-spring habitats; elsewhere they are reported from Brazil, Israel, Japan, and Australia among others. The FWS classifies the history of invasiveness as 'high' due to documented impacts on native species.

Breeding

Arguably the easiest cichlid to breed in home aquariums. A mature pair (sexual maturity at 4 to 6 months) in a tank with a suitable cave (a flat stone, an inverted ceramic flowerpot, or even a PVC elbow) will spawn with no special conditioning or water-chemistry manipulation. After a few days of mutual courtship involving brushing and quivering against each other, the female lays approximately 100 to 150 eggs (Mendoza et al. 2015) on the wall or ceiling of the cave; the male fertilises them. Both parents guard the clutch and aggressively expel intruders, and the eggs hatch in about 72 hours at typical aquarium temperature. Fry become free-swimming after another four to five days and are then shepherded around the tank by both parents in a tight cloud, with the male typically taking the outer perimeter and territory defense while the female stays close to the fry; the pair switch roles occasionally. Parental care continues for around four to six weeks. Fry accept baby brine shrimp and finely crushed flake from their first feeding. The pair will repeat-spawn every three to four weeks if conditions remain stable; convicts often practice serial monogamy in the wild, switching mates between broods (Snekser & Itzkowitz 2019 PeerJ). The hard part of breeding convicts is not getting them to spawn but managing the consequences: a single productive pair floods any tank with offspring, and fish stores almost never want them. Plan rehoming or culling upfront.

Common problems

Aggression during breeding is the primary management issue. A pair on eggs or fry attacks anything in the tank regardless of size, including catfish twice their length. Community setups become unliveable for tankmates once a pair forms, so most experienced keepers either dedicate a species tank to a breeding pair or accept that no other fish will thrive long-term in the same tank. A minimum of 150 to 200 litres with strong line-of-sight breaks is needed even for a single pair; smaller tanks produce constant chasing and injuries. Hybridisation is a real risk when housed with other Central American cichlids (firemouth, jack dempsey, salvini); the resulting hybrid offspring are nearly impossible to rehome and contribute to taxonomic confusion if released. Overpopulation from uncontrolled breeding is the most common practical headache: a pair spawning every three to four weeks rapidly produces hundreds of fish that no one wants. Diseases are rare because the species is among the hardiest aquarium fish; ich, columnaris, and fin rot appear only in seriously neglected tanks, and the species tolerates standard medications well. Released convicts establish self-sustaining populations in any warm water; the FWS rates the invasion risk as high, and responsible keepers do not release surplus stock.

Bioload

Further reading

• How to cycle a fish tank
• Stocking ideas by tank size