A robust, highly territorial Central American cichlid named after the aggressive 1920s boxer, William 'Jack' Dempsey. They exhibit beautiful iridescent blue, green, and gold spangling over a dark background. As aggressive diggers and plant destroyers, they require a tank with sturdy decor. They are best kept as a single wet pet or in a large tank with other similarly sized, robust Central American cichlids.
Jack Dempsey At a Glance
Jack Dempsey Tank Requirements
Will Jack Dempsey fit in your tank?
Care guides tell you what Jack Dempsey needs, the next question is whether your tank can safely provide it. Test Jack Dempsey against your tank size, maintenance needs, and the fish you already keep before you buy.
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Jack Dempsey Water Parameters
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Jack Dempsey Temperament & Compatibility
Jack Dempsey Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Standard Adult
The standard wild-type coloration and adult size. Highly aggressive and requires a very large footprint.
Same care requirements as the base species
Also known as: Wild Type, Regular Jack Dempsey
Juvenile (Grow-out)
Juvenile Jack Dempseys are frequently sold at 4-5cm. They can be temporarily housed in smaller aquariums but will grow quickly and become increasingly territorial as they mature.
Differs in 6 traits from base species
Also known as: Baby JD, Young Jack Dempsey
Electric Blue (EBJD)
A brilliant neon blue morphological variant. The EBJD is significantly smaller, much more peaceful, and notoriously more fragile than the wild type. They grow slower and are prone to parasitic infections and internal issues.
Differs in 4 traits from base species
Also known as: EBJD, Blue Jack Dempsey, Electric Blue
Jack Dempsey Care Guide Summary
The Jack Dempsey, scientifically known as Rocio octofasciata, belongs to the Cichlids - Central American family group. Adults reach a maximum size of approximately 25 cm and have a compressed body shape with a moderate growth rate. Classified as aggressive, this species primarily occupies the mid-level and bottom zones of the aquarium and produces a high level of biological waste.
To thrive, the Jack Dempsey requires a freshwater only aquarium with a minimum volume of 200 litres and a tank length of at least 120 cm. Water temperature should be maintained between 22°C and 30°C, with a pH range of 6.5–8 and a general hardness of 5–15 dGH. A moderate water flow is preferred.
Due to its specialist needs, the Jack Dempsey is best suited for fishkeepers who can provide a carefully planned setup. This species is available in 3 varieties: Standard Adult, Juvenile (Grow-out), and Electric Blue (EBJD). Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Jack Dempsey Habitat Setup
When setting up an aquarium for the Jack Dempsey, a moderate water flow best suits their natural preferences. Because this species occupies the mid-level and bottom zones, the aquarium layout should prioritise open swimming space in the centre of the tank for free movement and sufficient floor space with hiding spots among rocks, wood, or dense planting. Useful additions include a sand substrate to accommodate their sifting behaviour, smooth gravel or rounded substrate to protect their sensitive barbels, and driftwood, which can serve as both a hiding place and a dietary supplement. Keepers should note that expect substrate disturbance, so lightweight décor should be secured and live planted layouts may be difficult to maintain, as this species tends to uproot or consume vegetation.
Jack Dempsey Compatibility Notes
Classified as aggressive, the Jack Dempsey is adaptable and can be kept singly or in a small group, offering flexibility when planning a community tank. When choosing tankmates, any fish small enough to fit in its mouth will likely be eaten, conspecific aggression can be intense, especially in smaller tanks, and territorial behaviour may cause issues if hiding spots or floor space are limited. Selecting tankmates that favour different water layers from the mid-level and bottom zones can help reduce competition and territorial overlap.
Jack Dempsey Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Jack Dempsey.
55 Gallon Standard
60 Gallon Breeder
75 Gallon Standard
90 Gallon Standard
125 Gallon Standard
150 Gallon High
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Frequently Asked Questions About Jack Dempsey
How big does Jack Dempsey get?
Jack Dempsey (Rocio octofasciata) typically reaches a maximum adult size of approximately 25 cm. They have a compressed body shape and a moderate growth rate.
What tank size does Jack Dempsey need?
A minimum aquarium volume of 200 litres and a tank length of at least 120 cm are recommended for Jack Dempsey. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Jack Dempsey need?
Jack Dempsey thrives in freshwater only conditions with a temperature range of 22–30°C, a pH between 6.5 and 8, and a general hardness of 5–15 dGH. A moderate water flow is preferred.
Is Jack Dempsey peaceful or aggressive?
Jack Dempsey is classified as aggressive with an aggression score of 8 out of 10. Careful tankmate selection is essential to avoid conflict.
Can Jack Dempsey live alone?
Yes, Jack Dempsey can be kept singly or in a group. They are flexible and adapt well to both setups.
Does Jack Dempsey have any special tank requirements?
Yes. Jack Dempsey benefits from sand (sifters), driftwood (digestion/hiding), and smooth gravel (sensitive barbels) in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Plants That Suit Jack Dempsey
These plants pair well with Jack Dempsey based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Afzel's Anubias
Anubias afzelii
Anubias Barteri
Anubias barteri
Belinda's Buce
Bucephalandra belindae
Buce Motleyana
Bucephalandra motleyana
Congo Anubias
Anubias heterophylla
Dwarf Buce
Bucephalandra pygmaea
Fish Similar to Jack Dempsey
Cutteri Cichlid
Amatitlania cutteri
A stunning, robust Central American cichlid known for its striking blue eyes, vertical barring, and metallic sheen. While generally considered less aggressive than its close cousin the Convict Cichlid, it is highly territorial during breeding. They form monogamous pairs and are excellent, albeit fierce, parents that will actively dig out spawning pits.
Macaw Cichlid
Hypsophrys nicaraguensis
A robust and stunning Central American cichlid. Uniquely among many cichlids, the females are actually more vibrantly colored than the males. They are notorious diggers and cave-spawners that will rearrange substrate. Best kept with other similarly sized, robust Central American cichlids in a large tank.
Black Belt Cichlid
Vieja maculicauda
A large, powerful, and strikingly colored Central American cichlid known for the distinctive vertical black band across its midsection and vivid red flushing on its throat and tail. They are highly territorial, aggressive, and notorious for re-arranging the aquarium. They are primarily herbivorous in the wild but will eat almost anything, including smaller fish. They cannot be kept in planted tanks.
Pastel Cichlid
Cribroheros alfari
A strikingly beautiful Central American cichlid known for its pastel yellow, pink, and blue iridescent coloration. It is a substrate-sifting species that loves to dig in sand. Like many Central American cichlids, it can be highly territorial and aggressive, especially during breeding. Requires robust filtration and spacious quarters.
Red Devil Cichlid
Amphilophus labiatus
A massive, extremely aggressive Central American cichlid. Aptly named, the Red Devil is highly intelligent, interactive, and famous for 'glass-banging' at their owners. They are powerful diggers that will uproot plants and rearrange decor. Because of their sheer aggression and jaw strength, they are almost exclusively kept as 'wet pets' in solitary setups.
Green Terror
Andinoacara rivulatus
A large, incredibly colorful, and highly aggressive South American cichlid. Known for their striking metallic green/blue scales and vibrant orange or white tail margins. As their name suggests, they are highly territorial and require very careful tankmate selection, usually only coexisting with other large, robust cichlids or armored catfish in very large tanks.