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 Furry Diary remembers it for you
A typical home-care rhythm for a Jack Dempsey. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- 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
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- 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.