Jack Dempsey
Rocio octofasciata
Cichlidae
About
The Jack Dempsey is a stocky, boldly patterned Central American cichlid from the warm, weedy, mud-bottomed canals and slow lower river valleys running from southern Mexico down into Honduras. Named after the hard-hitting boxing champion for its pugnacious streak, it is hardy and long-lived but genuinely aggressive and strongly territorial, especially once it matures or pairs off to spawn. It is a substrate spawner that digs constantly, uproots plants and will hunt any tankmate small enough to swallow.
Care
Give a single fish or a bonded pair a long tank of at least 250 L (120 cm base) with sand, sturdy rockwork and caves for territory boundaries, plus strong filtration and weekly water changes. House only with robust, similarly sized tankmates and expect heightened aggression when breeding.
Diet
Predatory carnivore that eats worms, crustaceans, insects and small fish. Staple on a quality cichlid pellet and supplement with frozen or live bloodworm, mosquito larvae, prawn and earthworm; keep portions measured.
Tankmate compatibility
Possible with care (130)
Avoid (141)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Extended finsStrong · from about 8 months, and later in a suppressed male
On many cichlids and killifish the male's dorsal and anal fins draw out into trailing points as he matures, while the female's stay rounded.
- VentingA hint only · only on a mature fish, easiest when she is in breeding condition
The method breeders use when the answer has to be right. Hold the fish upside down in a wet hand or soft net and look at the two openings ahead of the anal fin. The forward one is the anus; the one behind it is what you are reading.
- Adult sizeA hint only · only across animals of the same age
In many cichlids, catfish and loaches one sex simply grows larger — usually the male, though there are well-known reversals.
Frequently asked questions
- What tank size does a Jack Dempsey need?
- A Jack Dempsey needs an aquarium of at least 250 litres (66 US gallons) with a footprint at least 120 cm (47.2 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Jack Dempsey need?
- Jack Dempsey does best at 22–30 °C (71.6–86 °F), pH 6.5–8 and a general hardness of 6–20 °dGH.
- Is the Jack Dempsey suitable for beginners?
- Jack Dempsey sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.