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.
At a Glance
Tank Requirements
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Water Parameters
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Temperament & Compatibility
Available 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. An aquarium test kit can help you monitor these values.
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. Browse aquarium sand substrate options to find the best fit.
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.
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
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.
Similar Species
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
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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.
Texas Cichlid
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The Texas Cichlid is the only cichlid species native to the United States. Known for their striking pearlescent blue/green spots and extreme territorial behavior, they require large tanks and robust filtration. They are notorious for rearranging aquariums, digging massive pits, and destroying live plants.
Firemouth Cichlid
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A popular Central American cichlid famous for the bright red coloration on its throat and belly, which it flares to intimidate rivals. They are earth-eaters, constantly sifting sand for food. While territorial, especially during breeding, they are relatively peaceful for a cichlid of their size compared to larger Central American counterparts.
Jaguar Cichlid
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Convict Cichlid
Amatitlania nigrofasciata
One of the most ubiquitous and hardy cichlids in the hobby. Named for their black-and-white prison stripe pattern, Convicts are infamous for their intense aggression, especially when breeding (which they do readily). They are intelligent, wet pets that rearrange their tank décor constantly. Best kept in species-only tanks or with other robust Central American cichlids.