Convict Cichlid Care Guide

The convict is the fish behind the classic "why is everyone in my tank dead?" post. It is hardy, cheap, eats anything and is arguably the easiest cichlid in the hobby to breed - which is exactly the trap. Put a male and female together and they bond, spawn relentlessly, and turn a peaceful community into a war zone. It is a brilliant first cichlid for a species or pair tank, and a disaster anywhere else. Unusually for a fish, the female is the colourful sex, wearing an orange belly the drab grey male never gets.

Convict Cichlid at a glance

The sourced figures the welfare engine uses to judge Convict Cichlid — the parseable key facts.

Where it comes from

Convicts are Central American cichlids from the streams, rivers, ponds and lakes of Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica and Panama, on both the Pacific and Atlantic slopes. They are benthopelagic and, in FishBase's words, almost never found in open water - they stick to rocky areas full of cracks, crevices, roots and debris that double as cover and spawning caves. That biotope explains the care almost completely. The cave-seeking habit is why a tank needs rock piles, flowerpots and driftwood, and why a bonded pair will fortress a corner. Their wild water is neutral-to-alkaline and medium-hard, so there is no soft-water fussiness - typical tap water suits them, part of why they are so forgiving. They even colonise high-elevation volcanic lakes, which is a clue to their wide thermal tolerance, their hardiness, and their notoriety as a global invasive. Never release one.

Did you know?

• It is named for a prison uniform - the black-on-grey vertical bars - and nigrofasciatus literally means "black-striped."
• The female is the flashy one, wearing the orange-pink belly and dorsal colour while the male stays drab grey: a genuine rarity among fish.
• It is one of the most-studied fish in behavioural biology, a model species for monogamy, mate choice, biparental and even adopted-brood care, and aggression.
• Mother and father split the parenting - she fans the eggs day and night (using smell in the dark), he patrols and fights off intruders, and they scoop stray fry back by mouth.
• It breeds itself out of demand: so prolific in captivity that convict fry have almost no resale value, and so tough that it has become an established invasive as far afield as Australia and Japan.

Tank size — and why

Sources spread from a 20-gallon bare minimum (Wikipedia) through a roughly 24-gallon footprint (Seriously Fish's 90 by 30 cm) to a hobby consensus of 30-40 gallons for a pair, so around 30-40 gallons is the honest recommendation; 20 gallons is a floor for a single fish or a short-term pair only. The driver is territory and aggression, not swimming distance. A breeding pair defends a patch and attacks anything that enters it, so floor area and line-of-sight breaks - rocks, caves, plants - matter far more than height, and bigger tanks make convicts noticeably less territorial. They are also heavy, digging, food-motivated fish with a high bioload, so size the filtration and water changes generously.

Keep a single Convict Cichlid — its own kind fight, so the answer is one regardless of tank size, with non-rival tankmates added only in a larger, planted tank.

How big does it really get?

Full-grown Convict Cichlid reach about 12 cm (4.7 in) long, but they are usually sold at only about 2.5 cm (1 in) — a typical shop size (estimate). At full size, Convict Cichlid needs roughly a 40-gallon tank, about 91 cm long; a common 10-gallon starter kit is only about 51 cm.

Adult size is sourced; the shop size is a typical-juvenile estimate; tank length is approximate for a standard 40-gallon aquarium.

Water parameters in practice

This is close to the opposite of a delicate fish. Aim for 24-28 C and a neutral-to-alkaline pH of about 6.5-8.0 in medium-hard water, but the tolerated band is huge - FishBase records survival from roughly 20 to 36 C and the species shrugs off parameter swings that would kill a ram. There is no need to soften or acidify. The one parameter worth managing deliberately is temperature for behaviour rather than health: convicts are measurably more aggressive at around 30 C, the temperature they prefer to spawn at, so keeping the tank toward the cooler end of the range helps damp the fighting. Otherwise standard good husbandry - zero ammonia and nitrite, regular water changes to keep up with the high bioload - is all they ask.

Diet & feeding

In the wild convicts are opportunistic omnivores; FishBase lists worms, crustaceans, insects, plant matter and fish in the diet. In the tank they are, as Seriously Fish puts it, very unfussy and will accept most foods offered. Run a quality sinking cichlid pellet or granule as the base and add variety - frozen or live bloodworm, brine shrimp, daphnia, tubifex and small worms - plus vegetable matter such as blanched peas, spinach, courgette or spirulina to balance the omnivore diet. Feed once or twice a day and do not overfeed, given the heavy waste output. Be warned that they are bold, confident feeders that will out-muscle gentler fish at the surface, and that the diet genuinely includes small fish: anything small enough to swallow is food.

Gear & setup

Give them a digging-friendly setup: sand or smooth fine gravel rather than coarse gravel, which can scratch them, and plenty of caves - flowerpots on their side, rock piles and driftwood - as spawning sites and refuges that also break up sightlines and dilute aggression. Use only robust or plastic plants such as java fern, anubias or water sprite, because convicts dig and graze soft plants. Strong external filtration suits the high bioload; avoid undergravel filters, which a digger will undermine. Keep the tank covered, as with any cichlid.

Temperament & behaviour

The headline trait is aggression. Seriously Fish describes an aggressive, territorial species that becomes downright violent when breeding and is not a good community fish. Outside breeding a single convict is bold and boisterous; the moment a pair spawns, the whole tank becomes a nursery to defend and they will drive off or kill anything they can catch, conspecific or not. This is the mechanism behind the community wipe-outs. Aggression scales with temperature (worse near 30 C) and inversely with space and cover, so a cramped, bare tank concentrates it. They are also conspecific-aggressive: any convict that is not a bonded mate - and especially a second male - is likely to be attacked, and a mismatched pair can end with one fish killing the other.

Group & social needs

Keep convicts singly or as a single bonded male-female pair. They are not a shoaling fish, and you cannot reliably crowd several together - extra or unpaired conspecifics get harassed and sometimes killed. A pair forms a strong, serially monogamous bond (re-pairing between broods is normal and, the research suggests, beneficial). The catch is that pairing one male with one female is also the switch that triggers relentless breeding aggression, so the calmest multi-fish option - a single sex or a single fish - is sometimes the kindest one.

Compatible tank mates (preview)

The engine clears no fish into a clear top set with Convict Cichlid. It is not a species you can stock from a generic "peaceful community" list — shrimp, snails and small community fish are not safe defaults with it, so work from the temperament and tank-mate guidance in the sections above (and the full compatibility checker) rather than a quick shortlist.

This engine-cleared shortlist is Convict Cichlid's tankmate surface for now — a dedicated tank-mates guide can follow for high-demand species.

Breeding & sexing

Breeding is famously trivial: a male, a female, a cave and decent water and feeding, with no special conditioning needed. Sexing is unusually easy because the colour is reversed - the female is the bright one, with an orange-to-pink belly and orange into the dorsal fin, often with a dark spot in the dorsal, intensifying when she is in spawning condition; the male is larger, grey-blue with little orange, with pointed dorsal and anal fins and, with age, a fatty nuchal hump. They mature at around 16 weeks to six months and spawn in a cave or crevice, laying roughly 100-300 eggs that hatch in about three to four days, with excellent role-divided biparental care for several weeks - the female fanning and tending the brood, the male patrolling the perimeter. The warning that matters: in aquaria a pair re-spawns roughly every 12-13 days, so you get fry constantly, with almost no resale demand. Have a plan (separate the sexes, rehome, or accept predation) before you pair them.

Lifespan

Around 8-10 years is the widely repeated hobby figure, with the odd fish exceeding ten under excellent care - though note FishBase and Seriously Fish publish no longevity number, so treat the upper end as hobby consensus rather than hard fact. Convicts are genuinely robust and not prone to the sudden die-offs that plague delicate species. What shortens a life here is avoidable: chronically poor water or overcrowding, injuries from fighting in cramped or wrongly-stocked tanks, and the toll of non-stop breeding, which can wear a female down.

Common mistakes

• Putting them in a community tank. Convicts bully, kill and eat smaller or peaceful fish, and a breeding pair clears the tank - this is the defining "why is everyone dead?" mistake.
• Buying a male and a female "to be nice" in a mixed tank. They will pair, breed and wage war on every neighbour. If you do not want breeding aggression, keep one convict or a species tank.
• Underestimating breeding output. "Easy to breed" means fry every couple of weeks with nowhere to go and almost no resale value. Have a plan before you pair them.
• A tank that is too small or has no caves. Cramped, cave-less tanks concentrate aggression and cause injuries; give floor area and line-of-sight breaks.
• Reading "beginner-friendly" as "community-friendly." Convicts are easy to keep and a great first cichlid, but that hardiness is exactly what makes them a trap for newcomers who add them to a peaceful tank.

Signs of trouble

• Torn fins, mouth injuries or a cowering, hiding tankmate - the most convict-specific problem is physical damage from aggression, not disease.
• Loss of colour, clamped fins and hiding in an otherwise bold fish - general stress, often from poor water or being on the receiving end of a fight.
• Refusing food and rapid gilling - check water quality first.
• White spots (ich) or head pits and stringy faeces (hole-in-the-head) - the usual stress- and water-quality-driven cichlid ailments, not unusually common here.
• A female that looks worn and thin after months of back-to-back spawns - breeding burnout; rest or separate the pair.

Is this fish right for you?

Do not buy a convict if you want a peaceful planted community - it will end in a depopulated tank. Do not buy a male and a female unless you actively want breeding, a species tank, and a plan for endless fry. Do not house it with small, slow, long-finned or timid fish (tetras, guppies, rasboras, corydoras, angelfish, gouramis), which get bullied, stressed, killed or eaten, and never add a second convict that is not a bonded mate. On stock quality there is little to fear: much trade stock is a hybrid of the split species (A. siquia, A. kanna) - fine as a pet, just not "pure" - and the pink/white/gold leucistic morphs are a recessive colour mutation, not a welfare-problem deformity like balloon or dyed fish. Do buy one if you want a hardy, characterful, easily-bred first cichlid for a species or pair tank and will never release the offspring.

Common questions

Are convict cichlids good for beginners?

Yes for keeping, no for a community. They are hardy, eat anything, tolerate a wide range of water and are arguably the easiest cichlid to breed, which makes them a great first cichlid in a species or pair tank. They are a trap in a peaceful community, where they bully, kill and eat the other fish, so the honest answer separates "easy to keep" from "safe with others."

Why is everything in my tank dying with a convict?

Because the convict - especially a breeding pair - is killing or eating it. They are territorial and become downright violent when spawning, defending the whole tank against everything they can catch. The fix is a species or pair tank, or only large, robust cichlids in a much bigger aquarium.

How can I tell a male convict from a female?

The colour is reversed from most fish: the female is the bright one, with an orange-to-pink belly and orange in the dorsal fin (often with a dark dorsal spot), intensifying when she is ready to spawn. The male is larger and grey-blue with little orange, with pointed dorsal and anal fins and, with age, a fatty hump on the forehead.

How many convict cichlids should I keep?

One, or a single bonded male-female pair. They are not a shoaling fish, and any extra or unpaired convict - especially a second male - is likely to be attacked. Be aware that a true pair is also the switch for relentless breeding aggression.

What water do convict cichlids need?

They are very forgiving - 24-28 C, neutral-to-alkaline pH around 6.5-8.0, medium-hard water, no softening needed. Keep the tank toward the cooler end of the range, because they get measurably more aggressive near 30 C, the temperature they prefer for spawning.

Sources & confidence

Sources & confidence (1 species)

These back the Convict Cichlid figures and the previewed tank mates above. Each figure is read from the TankStocking species database (v2026.06); below is the care reference behind it and how confident we are in that data. Confidence reflects the source quality, not whether any pairing is safe. Full source list and the welfare model are on the methodology page.

• Convict Cichlid Amatitlania nigrofasciata — Seriously Fish (seriouslyfish.com/species/amatitlania-nigrofasciata) high confidence

Care-guide sources (7)

This guide synthesises the references below; where they disagree, the range and the disagreement are noted in the text above. The figures in the key-facts box are read from the TankStocking species database (v2026.06). Full welfare model on the methodology page.

• FishBase - Amatitlania nigrofasciata
• Seriously Fish - Amatitlania nigrofasciata
• Wikipedia - Convict cichlid
• Snekser & Itzkowitz (2019), PeerJ - Serial monogamy benefits both sexes in the biparental convict cichlid
• AquariumSource - Convict Cichlid 101
• AquariumStoreDepot - Convict Cichlid Care
• Nature Communications (2021) - convict cichlid prosocial behaviour study

More on Convict Cichlid

Related guides on TankStocking — each scored by the same welfare engine as the planner.

This care guide is a sourced planning reference, not veterinary advice — individual fish, filtration and maintenance all matter. Cycle the tank, test your water, and observe your fish. How TankStocking works →