Jack Dempsey
A dark cichlid covered in blue-green spangles that intensify with age and condition, named after a heavyweight boxer for reasons the fish generally lives up to. It is one of the most widely available large American cichlids and one of the most consistently underestimated.
Quick profile
- Scientific name
- Rocio octofasciata
- Adult size
- 18–22 cm (7.1–8.7 in)
- Lifespan
- 8–14 years
- Temperature
- 24–29 °C (75–84 °F)
- pH
- 6.5–8
- Hardness
- 5–20 °dGH
- Minimum tank
- 300 L (79 US gal)
- Minimum length
- 120 cm
- Swimming zone
- All levels
- Social
- Pair
- Diet
- Carnivore
- Overall confidence
- moderate confidence
What keeping this species involves
Extremely hardy and long-lived, and difficult only in what it does to other fish. The commitment is more than a decade at twenty centimetres.
Slow, warm, often turbid lowland waters: canals, swamps and river backwaters with soft bottoms and heavy cover.
Identity and names
- Common name
- Jack Dempsey
- Scientific name
- Rocio octofasciata
- Family
- Cichlidae
- Order
- Cichliformes
- Class
- Actinopterygii
- Also sold as
- Rocio octofasciata, Cichlasoma octofasciatum, Nandopsis octofasciata, dempsey
- Former or synonymous names
- Cichlasoma octofasciatum, Nandopsis octofasciata
Varieties and strains
| Variety | What it means in practice |
|---|---|
| Electric blue | A recessive colour line, uniformly pale blue. Reported to grow more slowly, reach a smaller adult size and be less robust than the wild form, so its requirements are not identical to the record above. |
Adult size and growth
18–22 cm (7.1–8.7 in)
Typical lifespan in an aquarium: 8–14 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 large — a piscivore's mouth. A large-mouthed Central American.
Water and tank requirements
A twenty-centimetre cichlid that holds ground and pursues. The footprint is what allows anything sharing the tank to be outside the claimed area.
Temperature (°C)
Scale: 0 to 36 °C.
pH (pH)
Scale: 4 to 9.5 pH.
Hardness (°dGH)
Scale: 0 to 30 °dGH.
Why these ranges: Lowland Central American waters, warm and variable in hardness. This species is genuinely indifferent within that band, which is why it survives in conditions that suit it poorly for years.
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.
- TemperatureReasoned on this record
- This record states its own reason for this band. See the water section.
- pHReasoned on this record
- This record states its own reason for this band. See the water section.
- General hardnessReasoned on this record
- This record states its own reason for this band. See the water section.
| Requirement | Value | Notes |
|---|---|---|
| Temperature | 24–29 °C (75–84 °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 | 5–20 °dGH | Check your supplier's published figure before choosing species. |
| Minimum volume | 300 L (79 US gal) | A floor, not a recommendation. |
| Minimum footprint | 120 cm long × 50 cm deep | A twenty-centimetre cichlid that holds ground and pursues. The footprint is what allows anything sharing the tank to be outside the claimed area. |
| Water flow | low | Match the outflow to this rather than to the filter's rating. |
| Lid required | Recommended | Reduces evaporation and prevents accidents. |
| Structure | Caves, wood and open sand. Planting has to be robust or absent, and rockwork must be founded on the base glass rather than on substrate the fish will dig out. |
Behaviour
- Excavates pits against the glass and under decor, and will move surprisingly large stones.
- Darkens dramatically when defensive and pales when displaying, so a fish's colour reads its mood rather than its health.
Telling males from females
Males are larger with pointed dorsal and anal fins and more extensive spangling; females are smaller with rounder fins and often darker bodies when guarding.
Feeding
An opportunistic predator of insects, crustaceans and small fish. It takes prepared food well and is easily overfed, which shows first as a distended abdomen rather than as visible fat.
- Diet type
- Carnivore
- Staples
- Sinking cichlid pellets, Earthworm, Frozen krill, Frozen mysis
- Avoid
- Mammalian meat, Live feeder fish
Breeding
- Strategy
- Adhesive eggs on a cleaned flat surface, guarded by both parents
- Difficulty
- incidental
- Parental care
- guarding
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.
| Towards | Risk | What it means |
|---|---|---|
| Small fish | near-certain | 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.
- The electric blue form is a recessive line-bred variety that is slower-growing, less robust and more prone to swim-bladder problems than the wild form. Its appearance is the reason it is bred and it is not a better fish.
- Established outside its native range in Australia and in parts of the United States, where aquarium release is the recorded route.
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
- Atlantic slope of Central America — southern Mexico, Guatemala, Honduras and Belize
- Habitat
- Slow, warm, often turbid lowland waters: canals, swamps and river backwaters with soft bottoms and heavy cover.
What the checklists say
14 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 |
|---|---|---|
| Native | 1 | A checklist states the species occurs here naturally. |
| Introduced | 9 | 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 | 4 | The source records the species as present and does not say whether it is native or introduced. AquariumHQ does not fill that in. |
Legal status and responsible practice
Restriction note
Established from aquarium releases in several warm regions including parts of Australia and the southern United States. Local restrictions on possession or release vary and should be checked directly.
Where this species has been introduced, and what followed
Florida and elsewhere in the southern United States
Locally establishedLikely aquarium release in most cases, with aquaculture escape possible in areas of Florida adjacent to current or former production facilities.
- Deliberate aquarium releaseSomebody took the animal out of a tank and put it into open water. The commonest reason is that the fish outgrew the aquarium, which is why size at maturity is a conservation question as well as a welfare one.
- Escape from an ornamental fish farmOrnamental fish farms are usually outdoor ponds in warm places, and warm places are where tropical species establish. Several of the best-known Florida introductions began this way rather than with a keeper.
What has been established
- Predation on native speciesInferred from the animal's biologyNAS states only that omnivorous, opportunistic feeding should enhance its survival where introduced. That is a prediction about the fish rather than a finding about the water.USGS Nonindigenous Aquatic Species database credits: Jennings 1986
USGS Nonindigenous Aquatic Species database · Species Profile — Means of Introduction; Species Profile — Impact of Introduction · read 2026-08-29. A United States database: the routes and effects recorded here are the ones documented there, and say nothing about other regions.
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 | Rocio octofasciata | Observed / measured | high confidence | Catalogue of Life; GBIF — Global Biodiversity Information Facility |
| native range | Atlantic slope of Central America — southern Mexico, Guatemala, Honduras and Belize | Observed / measured | moderate confidence | GBIF — Global Biodiversity Information Facility |
| adult size | 18–22 cm | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| lifespan | 8–14 years | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| temperature | 24–29 °C | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| ph | 6.5–8 pH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| general hardness | 5–20 °dGH | Aquarium-literature consensus | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank volume | ≥ 300 L | AquariumHQ editorial position | moderate confidence | AquariumHQ husbandry synthesis |
| minimum tank length | ≥ 120 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 gbif on 2026-08-29. 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. 14 distribution statements held from GBIF checklists — native in 1, introduced in 9 countries. 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 sizeOne sourceAquariumHQ's own position, derived from evidenced inputs.1 citation, 1 independent origin
A single source: clofsca-2003.
- 25 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. A documented maximum is held and the catalogue's typical adult range is stated separately, with the relationship between them recorded rather than collapsed. The largest recorded specimen exceeds the typical adult size by a normal margin. Most individuals will not approach it, and it is not a planning figure.
What would improve this: Corroborate against a second, independent source.
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.
temperatureAquariumHQ'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.
phAquariumHQ'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.
general hardnessAquariumHQ'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.
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 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.
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.
- Wild conditions and aquarium recommendationsThe water band on this page is an AquariumHQ position with a stated reason, not a measurement of a river.
- Why fish size figures disagreeA documented maximum and a typical adult size are both held for this species, and they are different quantities.
- How aquarium species get into the wildThis species has a documented introduction outside its native range, with the route recorded.
- 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.
Group size and social behaviour
Territorial towards its own species and towards anything of similar shape. A bonded pair works; two males do not, and a mismatched pair frequently ends with the female dead.