FishfreshwaterUndemandingHigh invasive risk

Convict cichlid

Extraordinarily hardy, extraordinarily prolific and extraordinarily aggressive for its size. A pair will breed within weeks, defend a third of a tank and produce more fry than anybody has a home for.

Quick profile

Scientific name: Amatitlania nigrofasciata
Adult size: 10–15 cm (3.9–5.9 in)
Lifespan: 8–10 years
Temperature: 21–29 °C (70–84 °F)
pH: 6.5–8
Hardness: 6–25 °dGH
Minimum tank: 150 L (40 US gal)
Minimum length: 100 cm
Swimming zone: Bottom
Social: Pair
Diet: Omnivore
Overall confidence: high confidence

What keeping this species involves

Survives almost anything. The problem is what it does to its tankmates.

Streams and lakes with rock structure and moderate flow.

Identity and names

Common name: Convict cichlid
Scientific name: Amatitlania nigrofasciata
Family: Cichlidae
Order: Cichliformes
Class: Actinopterygii
Also sold as: zebra cichlid, black convict
Former or synonymous names: Cichlasoma nigrofasciatum, Archocentrus nigrofasciatus

Adult size and growth

10–15 cm (3.9–5.9 in)

Typical lifespan in an aquarium: 8–10 years. Almost every animal sold in a shop is a juvenile, so the tank has to suit the size in the first line rather than the size in the bag.

Shape, which is what the compatibility engine reads instead of length alone: deep-bodied with a moderate. Assigned from what is typical of Cichlidae, not examined for this species.

Water and tank requirements

A breeding pair holds a large territory and drives everything else away. A metre gives other occupants somewhere to be.

Temperature (°C)

Convict cichlid

21–29

Scale: 0 to 36 °C.

pH (pH)

Convict cichlid

6.5–8

Scale: 4 to 9.5 pH.

Hardness (°dGH)

Convict cichlid

6–25

Scale: 0 to 30 °dGH.

The bands AquariumHQ publishes for the convict cichlid, each drawn against the full range this catalogue uses for that parameter. A narrow band on a wide scale is a specialist; a wide one is a genuinely tolerant animal. Source: AquariumHQ husbandry position for this record — an editorial range, not a measurement

Where these figures come from

Habitat class

Hard alkaline water

Water draining limestone, gypsum or volcanic mineral — Central American rivers, karst springs, hard-water lakes.

These species are usually easy in hard tap water and difficult in the soft, acidic water the hobby treats as the default. The commonest failure is the keeper softening water that did not need softening.

Conductivity: 300–900 µS/cm
Flow: moderate
Dissolved oxygen: moderate
Seasonality: moderate

These are figures for the KIND of water body, not measurements of this species. They are AquariumHQ’s summary of the general limnology and are given wide because the water is.

TemperatureFollows the habitat this animal comes from: Follows the water this animal is recorded from — hard alkaline water. Hard alkaline water generally runs 22–30°C, and the advised band of 21–29°C is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species. A source does publish a figure for this parameter, and it answers a different question — an environmental range or a laboratory tolerance rather than a keeping recommendation. It is held alongside this band rather than behind it.
pHFollows the habitat this animal comes from: Follows the water this animal is recorded from — hard alkaline water. Hard alkaline water generally runs 7.4–8.5, and the advised band of 6.5–8 is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species. A source does publish a figure for this parameter, and it answers a different question — an environmental range or a laboratory tolerance rather than a keeping recommendation. It is held alongside this band rather than behind it.
General hardnessFollows the habitat this animal comes from: Follows the water this animal is recorded from — hard alkaline water. Hard alkaline water generally runs 10–25 dGH, and the advised band of 6–25 dGH is consistent with it. This is AquariumHQ's reasoning from the habitat, not a measurement of the species. A source does publish a figure for this parameter, and it answers a different question — an environmental range or a laboratory tolerance rather than a keeping recommendation. It is held alongside this band rather than behind it.

AquariumHQ advises

21–29

The habitatHard alkaline water

22–30

Scale: 19.7 to 31.4 °C.

Temperature: AquariumHQ's advised band against the habitat it is drawn from. Source: AquariumHQ advised range; habitat envelope is AquariumHQ's summary of the general limnology for this class of water body.

AquariumHQ advises

6.5–8

The habitatHard alkaline water

7.4–8.5

Scale: 6.2 to 8.8 pH.

pH: AquariumHQ's advised band against the habitat it is drawn from. Source: AquariumHQ advised range; habitat envelope is AquariumHQ's summary of the general limnology for this class of water body.

AquariumHQ advises

6–25

The habitatHard alkaline water

10–25

Scale: 3.2 to 27.9 dGH.

General hardness: AquariumHQ's advised band against the habitat it is drawn from. Source: AquariumHQ advised range; habitat envelope is AquariumHQ's summary of the general limnology for this class of water body.

Requirement	Value	Notes
Temperature	21–29 °C (70–84 °F)	Stability matters more than hitting an exact figure.
pH	6.5–8	A stable pH outside the ideal band is usually better than an unstable one inside it.
General hardness	6–25 °dGH	Check your supplier's published figure before choosing species.
Minimum volume	150 L (40 US gal)	A floor, not a recommendation.
Minimum footprint	100 cm long	A breeding pair holds a large territory and drives everything else away. A metre gives other occupants somewhere to be.
Water flow	moderate	Match the outflow to this rather than to the filter's rating.
Lid required	Recommended	Reduces evaporation and prevents accidents.
Structure	Rock caves and robust hardscape; plants are dug up.

Behaviour

Excavates the substrate thoroughly and uproots planting.

Telling males from females

Males are larger with pointed fins; females are smaller with orange belly scales.

Feeding

Diet type: Omnivore
Staples: Cichlid pellets, Frozen foods, Vegetable matter

Breeding

Strategy: Cave and substrate spawner; both parents guard aggressively
Difficulty: incidental
Parental care: guarding

Breeds relentlessly. Rehoming the fry is the real difficulty.

Tankmates and compatibility

Assessments are derived from stored traits by the compatibility engine, with the reasoning shown. A verdict is a statement about probability, not a guarantee — individual temperament can override it.

Risk this species poses to common tankmates
Towards	Risk	What it means
Small fish	high	Anything that fits in the mouth is at risk once this species reaches adult size.
Adult dwarf shrimp	near-certain	Cover reduces losses but rarely prevents them where the risk is high.
Shrimplets	near-certain	Determines whether a shrimp colony can grow rather than merely persist.
Snails	low	Applies to snails you wanted as well as snails you did not.
Long or trailing fins	occasional	Fin damage is an entry point for secondary infection.
Plants	uproots	Tough species such as Anubias and Java fern survive most grazers.

Assessed pairings

Any pair in the catalogue can be assessed with the compatibility checker.

Welfare considerations

Points where the way this species is commonly sold or kept differs from what it actually needs.

Established as an introduced species in warm waters worldwide, largely through aquarium releases.
Do not buy a pair unless you have decided in advance what happens to the fry.

Problems to watch for

Most problems in a tank containing this species are general rather than species-specific. Start with the troubleshooting index and work from the observation rather than from a guess at the cause.

What AquariumHQ does not yet hold

Species-level disease susceptibility is modelled in the graph and is not yet populated. Health pages will not be published until each condition has veterinary sourcing, because health content written without evidence is the most harmful thing this product could publish. The gap is recorded in the coverage report.

Where it comes from

Native range: Central America — Pacific and Atlantic slopes from Guatemala to Costa Rica
Habitat: Streams and lakes with rock structure and moderate flow.

What the checklists say

26 distribution statements retrieved from GBIF checklists. Establishment means is reproduced from the source where it states one, and left unstated where it does not — a record of presence is not a record of origin.

Status	Places	What this means
Introduced	23	A checklist states the species arrived here with human help. That is not a statement that it is established, harmful or illegal.
Recorded as present, establishment means not stated	3	The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in.

No checklist AquariumHQ holds positively calls this species native anywhere, so the native range above rests on AquariumHQ’s own reading of the literature rather than on a cited checklist.

Legal status and responsible practice

Restriction note

Established feral populations exist in several countries including parts of Australia and the United States, and possession or sale is restricted in some of them. Check the position in your jurisdiction before acquiring. Never release, and never dispose of fry into any watercourse.

Where this species has been introduced, and what followed

Europe — Italy from 2010, also Austria

Establishment unclear

Aquaculture escape, in two countries. As with the oscar, a Central American cichlid in Europe persists only where the water stays warm.

Escape from food or bait aquacultureFood and bait production, at a scale no private keeper approaches. The animals are held in numbers, in ponds, often on floodplains.

What has been established

Nothing. The species is present outside its native range and no study has measured what it does there. The absence of data is not the absence of effect — it means the question has not been asked, and this is the ordinary state of the evidence for most aquarium species that have established somewhere warm.

EASIN — European Alien Species Information Network · EASIN catalogue record R21309 (apixg/catxg) · read 2026-08-30. A European network: the routes and effects recorded here are the ones documented in Europe. EASIN compiles national inventories, DAISIE and CABI rather than measuring, and its pathway assignments carry its own uncertainty flags, which are reported above where it sets them.

What AquariumHQ has recorded, by jurisdiction, with the instrument each entry comes from and how far the check went. Ecological risk and legal status are separate: a species can be ecologically risky and legally unrestricted, or restricted where it could never establish.

AU

Prohibitedimport

A prolific, aggressive and highly adaptable cichlid with established populations in several warm regions. Australia's permitted-list regime does not admit it.

Instrument: Environment Protection and Biodiversity Conservation Act 1999 — List of Specimens taken to be Suitable for Live Import

Instrument recorded, species entry not re-checked · last checked 2026-08-11 · AquariumHQ has recorded the instrument and what it does, but has not re-confirmed this species' entry against the current consolidated text. Listings are amended, so treat this as a pointer to the right law rather than as a confirmation of the current position, and check with the authority before acting.

US

Prohibitedrelease

Established in warm-water systems including geothermally influenced waters outside its native range. Its readiness to breed in captivity is exactly what makes an escaped population self-sustaining.

Instrument: State fish and wildlife regulations; established populations are documented in the USGS Nonindigenous Aquatic Species database

EU

Not verified by AquariumHQpossession

No restriction was identified in the sources AquariumHQ checked for the EU as of 2026-08-11. That is not a finding that keeping, selling or moving this species is lawful there: sub-national rules, permit regimes and trade-specific requirements exist that these sources do not cover, and lists are amended. Check with the relevant authority before acquiring, selling or moving any animal.

Never release aquarium life into the wild

Aquarium animals, plants, and aquarium water must never be released into ponds, rivers, canals, drains or the sea — not even in a country where the species is sold freely. Released fish and invertebrates establish populations that displace native species, and released plants and water carry pathogens, parasites and fragments capable of spreading without any animal at all. If you can no longer keep an animal, rehome it through an aquarium society, a retailer that accepts returns, or another keeper.

Rehome through a local aquarium society, a specialist retailer or another keeper.
Unwanted plants go in household waste or a hot compost heap, never in a watercourse or a garden pond.
Never empty a bucket of tank water into a drain that discharges to open water.
If an animal is beyond rehoming, ask an aquatic veterinarian about humane euthanasia rather than releasing it.

Legal status is recorded from the sources named and was correct on the verification date shown. Rules change, and sub-national rules often differ from national ones. Check the current position with the relevant authority before acquiring, selling or moving any animal or plant.

Evidence

Every stored value with the kind of support behind it and where to check it. Evidence type and confidence are separate axes: an editorial position held confidently and a measurement held tentatively are different things.

Claim	Value	Evidence type	Confidence	Source
scientific name	Amatitlania nigrofasciata	Observed / measured	high confidence	Catalogue of Life; GBIF — Global Biodiversity Information Facility
native range	Central America — Pacific and Atlantic slopes from Guatemala to Costa Rica	Observed / measured	moderate confidence	GBIF — Global Biodiversity Information Facility
adult size	10–15 cm	Aquarium-literature consensus	high confidence	AquariumHQ husbandry synthesis
lifespan	8–10 years	Aquarium-literature consensus	high confidence	AquariumHQ husbandry synthesis
temperature	21–29 °C	Aquarium-literature consensus	high confidence	AquariumHQ husbandry synthesis
ph	6.5–8 pH	Aquarium-literature consensus	high confidence	AquariumHQ husbandry synthesis
general hardness	6–25 °dGH	Aquarium-literature consensus	high confidence	AquariumHQ husbandry synthesis
minimum tank volume	≥ 150 L	AquariumHQ editorial position	moderate confidence	AquariumHQ husbandry synthesis
minimum tank length	≥ 100 cm	AquariumHQ editorial position	moderate confidence	AquariumHQ husbandry synthesis

Last reviewed 2026-08-10. Values labelled as an aquarium-literature consensus are AquariumHQ editorial positions rather than measurements — see how evidence is handled.

Why we say this

What each figure on this page rests on, and how far that is from being independently established.

Every figure on this page has a provenance. Open any claim to see what AquariumHQ holds for it, which sources say what, and what a claim of that kind actually needs. Different claims need different evidence: an accepted scientific name is settled by one authority, while a legal restriction needs a current primary instrument. A single source is often the right answer rather than a thin one.

scientific nameAquariumHQ's own position, externally checkableBased on a verified authoritative source.

AquariumHQ's own position on a claim an external source could support.

What this kind of claim needs: accepted scientific name and classification — 1 authoritative source in an appropriate context. Checked against fishbase on 2026-08-11. One authoritative backbone is what this class requires.

What would improve this: Go and read a source. This is reachable and has not been reached.

native rangeAquariumHQ's own position, externally checkableBased on a verified authoritative source.

AquariumHQ's own position on a claim an external source could support.

What this kind of claim needs: where the species occurs — 1 authoritative source in an appropriate context. 26 distribution statements held from GBIF checklists — introduced in 21 country. Establishment means is reproduced from the source, never inferred from occurrence.

What would improve this: Go and read a source. This is reachable and has not been reached.

adult sizeSeveral sources, fewer originsBased on a verified authoritative source.2 citations, 1 independent origin

2 citations resolving to 1 origin. Agreement between sources that share a source is not corroboration.

10 cm — FishBase · Maximum recorded · The range the species is recorded from · checked 2026-08-11
10 cm — USGS Nonindigenous Aquatic Species database · Maximum recorded · Observed in the wild · checked 2026-08-29

What this kind of claim needs: size a well-kept specimen reaches — no external source is required, provided AquariumHQ shows its reasoning. One authoritative source, which is what this kind of claim requires. Independent replication would be welcome and is not the standard.

What would improve this: Find a genuinely independent source, or stop describing the agreement as consensus.

lifespanAquariumHQ's own position, externally checkableAquariumHQ's own position, derived from evidenced inputs.

AquariumHQ's own position on a claim an external source could support.

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. No external source is required for this class. AquariumHQ's position stands on its stated reasoning.

What would improve this: Go and read a source. This is reachable and has not been reached.

temperatureOne sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin

A single source: bussing-1998-costa-rica.

20–36 °C — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. Derived from the observed range rather than copied from it. The observed envelope spans conditions this species meets across seasons and localities; a keeper holds one temperature continuously. The advised band trims both ends because sustained residence at an extreme is a different demand from encountering it, and stability matters more to a captive fish than breadth.

What would improve this: Corroborate against a second, independent source.

phOne sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin

A single source: fishbase.

7–8 pH — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. Derived from the observed range rather than copied from it. The advised band reaches past the observed envelope and carries no individual review. Commercially bred stock is generally more tolerant than wild records suggest, which is the usual explanation, and it has not been established for this species.

What would improve this: Corroborate against a second, independent source.

general hardnessOne sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin

A single source: fishbase.

9–20 °dGH — FishBase · Tolerated range · The range the species is recorded from · checked 2026-08-11

What this kind of claim needs: what aquariumhq advises for keeping — no external source is required, provided AquariumHQ shows its reasoning. Derived from the observed range rather than copied from it. The advised band reaches past the observed envelope and carries no individual review. Commercially bred stock is generally more tolerant than wild records suggest, which is the usual explanation, and it has not been established for this species.

What would improve this: Corroborate against a second, independent source.

minimum tank volumeAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.

No external authority publishes this. The rationale carries the reasoning.

What this kind of claim needs: minimum tank size — no external source is required, provided AquariumHQ shows its reasoning. No authority publishes this. AquariumHQ derives it, and the derivation is recorded with its inputs and assumptions.

What would improve this: Keep the rationale current. There is no source to find.

minimum tank lengthAquariumHQ's judgement — no authority publishes thisAquariumHQ's own position, derived from evidenced inputs.

No external authority publishes this. The rationale carries the reasoning.

What would improve this: Keep the rationale current. There is no source to find.

Guides relevant to this species

Chosen from this record's own traits rather than listed on every page.

Predator and prey sizeIt takes fish that fit in its mouth, and its mouth grows with it.
Territorial behaviourIt defends ground, and the shape of what it defends decides the tank more than the volume does.
Native, introduced and invasiveThis record carries an invasive or legal note, and those are five separate claims that are easy to read as one.
Scientific and trade namesThis species has been published under more than one accepted name.
The kinds of water aquarium fish come fromThis record's water bands follow hard alkaline water, which is the kind of water this animal is recorded from.
How aquarium species get into the wildThis species has a documented introduction outside its native range, with the route recorded.
What a legal restriction on a species actually meansAquariumHQ holds a structured legal status for this species, and possession, sale, import and release are four separate questions.
How to read a compatibility verdictThis animal is recorded as nipping fins, which is one of the few compatibility factors with real reports behind it.

Convict cichlid

Quick profile

What keeping this species involves

Identity and names

Adult size and growth

Water and tank requirements

Where these figures come from

Group size and social behaviour

Behaviour

Telling males from females

Feeding

Breeding

Tankmates and compatibility

Assessed pairings

Welfare considerations

Problems to watch for

Where it comes from

What the checklists say

Legal status and responsible practice

Where this species has been introduced, and what followed

Europe — Italy from 2010, also Austria

What has been established

AU

US

EU

Evidence

Why we say this

Guides relevant to this species