Jack Dempsey
Rocio octofasciata
Min Tank Size
208L
Adult Size
25 cm
Lifespan
12 years
About
Named after the legendary heavyweight boxer, and it earns that title. Rocio octofasciata comes from the slow-moving rivers, lakes, and swamps of Central America, ranging from Mexico down through Honduras.
Wild specimens are a deep, almost black base color covered in shimmering blue-green and gold iridescent spangles that intensify dramatically under good lighting. Males develop extended finnage and a more pronounced forehead as they mature, and breeding-colored fish are genuinely stunning in a way that photos don't fully capture.
These are big cichlids. Adults routinely hit 18 to 20 centimeters, and they need water to match: a 208-liter tank is the floor, and more space is always better. Water parameters are fairly flexible, tolerating a pH between 6.5 and 8.0 and temperatures from 22 to 30 Celsius, which makes them adaptable to a wide range of tap water. They're messy eaters and produce significant waste, so robust filtration is non-negotiable. Feed a varied carnivore diet: quality pellets, earthworms, shrimp, and occasional cichlid sticks. Avoid feeder fish.
Don't let juveniles fool you. Young Jack Dempseys can seem almost manageable in a community setting, but as they grow and mature, territorial instincts kick in hard. They'll claim the bottom and middle of the tank as their own and defend it aggressively.
They're rewarding fish precisely because of this personality. There's something engaging about a fish that actually notices you and responds to its keeper. Check out real tank builds featuring Jack Dempseys to get a feel for how experienced hobbyists actually set up a tank around this species.
Water Parameters
Temperature
°CpH
GH
dGHKH
dKHSwimming Level
Flow Preference
Keeping multiple Jack Dempsey together
Jack Dempsey is strongly territorial. Multiples fight over space unless the tank is large enough for each to claim its own area. A single individual is the safer default.
Compatibility
Jack Dempseys do best with other large, robust Central or South American cichlids that can hold their own: Oscars, Green Terrors, Convicts, and similarly sized fish. Giant Gourami and large Plecos work as tankmates given enough space. Anything small, slow, or fancy-finned will be harassed or eaten. Avoid delicate fish entirely. In a very large tank, 400 liters or more, some hobbyists successfully keep them with robust mid-water schooling fish like large barbs or giant danios that are fast enough to avoid confrontation. Shrimp and snails are food. Any fish under 8 to 10 centimeters is a snack.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
The biggest beginner mistake is underestimating adult size and aggression. People buy a 5-centimeter juvenile for a 100-liter community tank and six months later have a problem. Filtration is the other common failure point: these fish eat a lot and produce waste to match, so running two filters is not overkill. Plants can work but expect them to be uprooted regularly during territorial behavior. Use hardy, rooted species like Amazon swords and weigh down pots. Water changes of 30 to 40 percent weekly are important to manage nitrates given the bioload.
Behavior & Aggression
Aggression peaks during spawning and when territory is established. They'll chase, ram, and shred fins on anything that enters their claimed space. Other large cichlids of similar size are the most likely to get into real trouble. Juveniles often coexist peacefully, which catches people off guard when they hit sexual maturity. Providing multiple hiding spots and broken lines of sight reduces tension significantly. Large tanks dilute aggression by giving other fish room to escape. Pairs can suddenly turn on each other after a failed spawn, sometimes fatally.
Things to Know
- Will rearrange substrate and uproot plants during territory claiming
- Pairs bond strongly but can turn on each other after spawning
- Gets significantly more aggressive as it matures, juveniles can be deceptive
- Not safe with any fish small enough to swallow
- Can be very aggressive, especially when breeding.
Community Sightings
No builds featuring this species yet.
Be the first to feature Jack Dempsey in your build →Discover Tanks
Explore more builds from the community.
Explore More Species
More species to discover.
