Should I buy it?
Jack Dempsey
Rocio octofasciata
Also known as: j.d., rio grande cichlid, J.D., Rio Grande cichlid
Fishori provides conservative planning guidance, not guarantees.
Based on multiple reputable aquarium care sources with strong agreement. Use the numbers here as planning defaults — your room, water, and routine still shape real-world outcomes.
Robust New World cichlid that develops electric blue spotting as it matures. But aggressive, large, and not community-safe.
Best for
Single-species or paired-cichlid setups of 300 L or more with serious filtration and rockwork.
Avoid if
You wanted a community fish, your tank is under 250L, or you can't manage cichlid aggression.
Top things that go wrong
- Grows large or needs a very big footprint. Jack Dempsey is often sold at sizes that hide adult length (~25cm on file) and a published minimum near **200L**. Shop tanks are not adult housing.
- Mouth gap vs tiny tank mates. Predation risk toward smaller tank mates. The figure that matters is the adult mouth size against the adult prey length, not the juvenile sizes in the shop.
- Shrimp & snails. Shrimp: not safe. The fish will eat adult shrimp, shrimp fry, or both, depending on the size of the shrimp.
Common mistakeBuying a pair for company. Two jack dempseys in 200 L fight until one is cornered. Even a matched bonded pair needs division of territory.
What most shops don't tell you
- 1.Predation risk scales with gape, night feeding, and crowding. 'they grew up together' is a schedule, not a law.
- 2.Buying for juvenile size in the shop tank. Budget for adult length and turning radius, not the inch-long fish in the bag.
- 3.Adding bite-sized tetras or livebearers "until the predator grows". The first lost fish lands months earlier than the plan said.
- 4.Not suitable for community tanks. Keep only with similar-sized aggressive cichlids or alone. Requires a large tank with hiding spots and robust decor.
About this species
Jack Dempseys are 20 to 25 cm Central American cichlids named for the boxer. Adults develop iridescent blue-green spotting and defend a territory hard, especially when breeding.
- African Cichlid200L min · same group, comparable tank size
- Convict cichlid200L min · same group, comparable tank size
- Discus200L min · same group, comparable tank size
- Firemouth Cichlid200L min · same group, comparable tank size
- Keyhole cichlid200L min · same group, comparable tank size
- Rainbow cichlid200L min · same group, comparable tank size
- Angelfish150L min · same fish family
- Electric Blue Acara150L min · same fish family
- African Cichlidalso intermediate aggressive, similar tank size
- Green Terroralso intermediate aggressive, similar tank size
- Oscaralso intermediate aggressive, similar tank size
- Common Pleco tank mateslists this fish as a safe and recommended mate
- Green Terror tank mateslists this fish as a safe and recommended mate
- Oscar tank mateslists this fish as a safe and recommended mate
Plan grid
Key limits are shown above; this section adds planning detail: pH band, swim level, bioload and activity, and the radar.
Swim zones
Planning trait chart
Six indices for comparing species on paper before you spend.
- Beginner ease26
- Peacefulness0
- Community fit0
- Small-tank fit80
- Hardiness54
- Energy54
Numbers are deterministic planning indices from Fishori fields — not a scientific score of your individual fish.
Common setup sketches
Conservative patterns from Fishori fields — still run the pair checker for every species you add; sketches are not a stocking guarantee.
Avoid “one of everything” baskets — Jack Dempsey belongs in a plan built around territory, line-of-sight breaks, and matched water chemistry.
Tank mate intelligence
Pair with similarly sized Central American cichlids (firemouth, convict in 500 L or more, severum) and large catfish. Anything under 8 cm is prey.
Pair-level compatibility with this fish as anchor.
Read the blocking rule on each pair page before experimenting.
Do-not-stock combinations on conservative hobby rules.
Compare with
Run a real pair check: Jack Dempsey + Oscar
- Try Oscar — open the pair check.
- Try Green Terror — open the pair check.
- Try Common Pleco — open the pair check.
Behaviour, temperament, and what to watch
Prose and lists come from the same record: read temperament first, then glass-level signals so you are not surprised after day three.
Aggressive and territorial. Calm for a few hours, then suddenly redecorating the tank. Pair them with their own kind or larger Central American cichlids only.
Stress / aggression triggers on file
- Crowding and limited territory
- Similar-looking fish in the same tank
- Spawning, for any breeding pair
Fin nipping: Not a habitual fin-nipper, but individuals can still test fins under stress or in a crowded tank.
Predation: Predation risk toward smaller tank mates. The figure that matters is the adult mouth size against the adult prey length, not the juvenile sizes in the shop.
Territory: Holds territory on substrate, in caves, or at the surface film. Break the line of sight with hardscape, and avoid placing the tank where the fish can see its own reflection.
Planted tanks: caution — pick tougher plants
In the glass: typical and warning signs
- Moderate pacing — not hyperactive, not motionless.
- Clamped fins, gasping at the surface, hiding non-stop, or refusing food after the first week.
- Rapid breathing when parameters swing — fix ammonia/nitrite first, then reassess mates.
- Chasing one individual repeatedly, torn fins on tank mates, or food theft every feed.
- Corner guarding, flaring, or body-blocking — territory is normal until it becomes relentless.
- Separate or rehome if injuries appear, one fish is pinned, or feeding becomes a daily chase.
- If water is stable but behaviour worsens, reduce stocking or remove the highest-impact species first.
Fish behaviour can vary between individuals and tank setups. Always observe new fish closely after introduction.
Care parameters: water, food, inverts, grouping
Chemistry and group rules sit here so you are not re-reading the same line from tank mate or temperament blocks. Swim level is in the plan grid above.
Hardness
variable
Diet
carnivore
Small invertebrates, frozen bloodworm or daphnia, and protein-rich prepared foods. Rotate the menu and feed by appetite rather than by clock.
Shrimp & snails
Shrimp: not safe. The fish will eat adult shrimp, shrimp fry, or both, depending on the size of the shrimp.
Kept singly or as a paired setup. Check the species profile before doubling up in one tank.
Breeding behaviour depends on the species. Research before you buy a mixed-sex group of this fish.
- Hold 22 to 28 °C steadily on a real thermometer, not the dial on the heater.
- Aim for pH 6.5 to 8 and a hardness you can re-test in two weeks. A one-time strip in the shop car park is not a water test.
- Footprint: short wide tanks and tall narrow tanks fish differently for the same volume. Match the tank shape to the swim pattern, not just the litre count.
- Tank volume meets or exceeds 200L published minimum for adults.
- Heater can hold 22–28°C without cooking cooler-water tank mates.
- No tank mates small enough to fit the adult mouth gap for this species.
Explore and stocking hubs
Same library as the rest of Fishori: tank-mate index for this species, category peers, guides, and litre-based stocking lists where min tank on file is within the hub volume.
Plan with tools
Pair-level rules and multi-fish stocking use the same conservative engine — add this fish in the tank builder only after mates pass pair checks.
Filtration & heating
A 200L minimum tank needs a filter rated for at least 800L/hr turnover and a heater to hold 22–28°C reliably.
Profile status: partially verified · Evidence tier: high · 3 linked source(s). Fishori does not fabricate citations.
Fishori uses conservative planning rules based on these sources.
Confidence is explained in the summary at the top of this page (same tier as here), not repeated below.
How Fishori evaluates compatibility (same logic as pair and tank tools).
- Seriously Fish. Rocio octofasciata
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Rocio octofasciata
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Rocio octofasciata
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Evidence notes
- The Seriously Fish profile for the binomial in this record was successfully reached as the primary aquarium reference.
- FishBase contributes natural-range size and habitat context. Translate those numbers through your heater, your water report, and your tank footprint before stocking.
- Wikipedia is only cited if the article URL returned OK. Use it for orientation, not as the only care sheet for an import.
- All compatibility text reflects typical hobby experience and the Fishori model. Individual fish, shop stress, and the order tank mates are added in can still defy a single-paragraph label.
- Fishori profiles work from typical aquarium trade sizes and hobby care norms. Specialist site checks and literature review for this species are not yet recorded here, so the ranges on this page are planning numbers rather than guarantees.