Not furry, but we like them anyway.
Jack Dempsey
Rocio octofasciata (Regan, 1903)
Also called Jack Dempsey cichlid, Electric blue Jack Dempsey (colour form), Mojarra castarrica
From Central America: Atlantic slope from southern Mexico (Veracruz) through Belize and Guatemala to western Honduras, in swamps, slow rivers, canals, lakes and ponds.123
At a glance the quick version
Wikipedia says it can live more than 10 years in aquariums
Looks how to spot one
Robust, stocky cichlid
A thickset cichlid with a strong head. Youngsters are pale grey with faint turquoise marks, and adults deepen to purple-grey covered in bright blue, green and gold flecks.32
Personality what they are like
A bold, territorial fish that gets more assertive as it matures; settled pairs are calm with each other. The electric blue form is described as gentler and smaller.23
Daily activity how busy a day looks
Moderately active, digs in the substrate and patrols its territory.2
Grooming and care the hands-on bits
Excellent water quality in a fully cycled tank with strong filtration; plants are best floating or tied to decor because it digs.2
Home where they are happiest
Minimum about 120 x 45 cm (around 240 litres) for an adult pair; soft sand, flat stones, driftwood and dim light. Water about 20 to 30 C, pH roughly 6.5 to 8.0, hardness 5 to 20 dGH.21
Food basics what goes in the bowl
Omnivore leaning to meaty foods: sinking cichlid pellets plus frozen shrimp, bloodworm, daphnia and mosquito larvae, with some vegetable or spirulina food.21
Company who they like around
Young fish can live in groups; adults are best kept as a pair or with large, robust tankmates in a spacious aquarium.2
The story where it all began
Charles Tate Regan described the species in 1903. Aquarists in the 1920s nicknamed it after the heavyweight boxer Jack Dempsey because of its strong face and feisty nature. A naturally occurring blue form was later developed into the popular electric blue strain.123
Fun facts for the dinner table
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 24 August 2018)1
- Taxonomy
- Described by Regan in 1903; previously in Heros, Cichlasoma, Archocentrus and Nandopsis, now in Rocio3
The care rhythm a typical week and year
A typical home-care rhythm for a Jack Dempsey. A starting point, not a vet's advice.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Water changeAbout 25% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseRinse in old tank water, never tap waterevery month
Owner questions the things everyone asks
How often should I feed my Jack Dempsey?
Furry Diary's starting plan is to feed small amounts once or twice a day. As an omnivore leaning to meaty foods, offer sinking cichlid pellets plus frozen shrimp, bloodworm, daphnia or mosquito larvae, with some vegetable or spirulina food. Always follow the food label and check with your vet for exact amounts.21 Pet Wiki plan
What does a Jack Dempsey eat, and what should it never eat?
Your Jack Dempsey enjoys sinking cichlid pellets, frozen shrimp, bloodworm, daphnia, mosquito larvae, and some vegetable or spirulina food. Avoid any foods not listed here, and never feed live prey that could carry disease or cause injury. For specific restrictions, ask your exotic-pet vet.21
How much space does a Jack Dempsey need?
An adult pair needs a minimum tank of about 120 x 45 cm (around 240 litres). Provide soft sand, flat stones, driftwood, and dim light. This gives them room to patrol and dig.21
What temperature, light or water does a Jack Dempsey need?
Keep water temperature between 20 and 30°C, pH roughly 6.5 to 8.0, and hardness 5 to 20 dGH. Use dim light and maintain excellent water quality in a fully cycled tank with strong filtration. Check temperature daily and test water weekly.21 Pet Wiki plan
How often should I clean a Jack Dempsey's home?
Furry Diary's plan suggests a weekly 25% water change, weekly glass cleaning, and a monthly filter rinse in old tank water (never tap water). This keeps the tank healthy for your fish. Pet Wiki plan
Can a Jack Dempsey live with others?
Young fish can live in groups, but adults are best kept as a pair or with large, robust tankmates in a spacious aquarium. They are territorial and get more assertive as they mature, so choose companions carefully.2
How long does a Jack Dempsey live?
With proper care, a Jack Dempsey can live up to 10 years. Providing a good diet, clean water, and suitable tankmates helps them reach this lifespan.3
Can I handle a Jack Dempsey?
It's best not to handle your Jack Dempsey, as it can cause stress and injury to the fish. Enjoy watching its bold personality and beautiful colors instead. For any health concerns, consult an exotic-pet vet.
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Pet Wiki's own starting care plan. A friendly guide, not a vet's advice.
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Green TerrorWhere this comes from
Every fact on this page has a numbered source. Spotted an error? support@petwiki.app.
- FishBase: Rocio octofasciata fishbase.seused for taxonomy, range, size, water, IUCN
- Seriously Fish: Rocio octofasciata seriouslyfish.comused for care, tank size, water, diet, behaviour, notes
- Wikipedia: Jack Dempsey (fish) en.wikipedia.orgused for name origin, lifespan, colour, breeding, fun facts
Checked 2026-09-30. Text is written in our own words from these sources.