Jack Dempsey

Aquarium fish: Jack Dempsey (Rocio octofasciata)
Size: 15 – 20 cm
Origin: South America
Water temperature: 22-30 ° C
Aquarium volume: 240 l

Jack Dempsey (Rocio octofasciata ) – a large, colorfully colored aquarium fish from the Cichlids family. Its common name, Jack Dempsey , comes from the name of an American boxer, the world heavyweight champion of the 1920s – probably due to the strong features of the face and aggressive character.


Central America. The species is found in Mexico, Belize, Guatemala and Honduras. Wild populations have also been established in the United States, Russia, Australia, and Thailand.

They are most commonly found in coastal and slow-flowing shallow rivers, as well as in artificial and river channels, drainage ditches, lakes and ponds.

Characteristics and disposition

Under good conditions , adult specimens can grow up to 25 cm in length . The fish are oval in shape, stocky and compact. The body of adult fish is dark purple-gray in color. Adult males have elongated, sharply pointed and red edged dorsal and anal fins.

Most of their bodies are covered with tiny spots, iridescent bright blue, green and gold. They can also have a round black spot in the center of the torso and at the base of the tail. Females have less colored dust on their bodies, and dark spots may appear on the dorsal fin and on the gill covers. The body of young cichlids is slightly gray or opalescent in color and covered with pale turquoise spots. The color of the fish can change significantly depending on age or mood.

When stressed, they will be paler and their pattern will be less visible. There is also a bright blue variety, the so-called Electric blue , the origin of which is not entirely clear, is probably an ornamental form obtained from a natural mutation.

Nutrition and feeding

In nature , they are omnivores , but the basis of their diet is invertebrates. In the aquarium, you can feed foods that sink to the bottom – dry, frozen, live, such as daphnia, mosquito larvae, bloodworm, shrimp. Home-made foods, mixtures of various ingredients, e.g.

fresh fruit, vegetables, spirulina and meat are also highly recommended.


For a pair of adult cichlids, an aquarium with a base of min. 120 × 45 cm, preferably with a soft, sandy surface and low light. One or two flat, smooth stones on which the fish spawn should be placed in the aquarium. Decorations of wood and twisted roots will give the tank a more natural look.

When it comes to plants, we should choose floating ones and those that grow attached to decorations – cichlids love to dig through the ground. They are sensitive to water pollution and should never be introduced into a biologically immature aquarium . They can be kept with other fish that will not fit into their mouths. With other cichlids they can only be kept in a sufficiently large aquarium. Young individuals can stay in a larger group, but after reaching sexual maturity they become aggressive towards each other.

The couple is gentle towards each other, but shows hostility towards their species as well as towards others who look like them.


A well-matched pair will be happy to breed in the aquarium . The matching process, however, can be risky. The safest and easiest method is to buy a group of young fish and pair naturally. The rest of the fish should be caught.

The water should be soft and acidic 6.5-7.0 pH at 24-27 ° C. The aquarium requires flat pebbles on which cichlids eagerly lay their eggs. They are stimulated for spawning by increasing the amount of live and frozen food given and by changing part of the water (30-50%) with a slightly cooler one than in the tank. The encouraged couple selects and clears a spawning ground. During the act, the female lays the eggs in line, and then gives way to the male, who flows over them and releases the milk.

During spawning, the female lays 500-800 eggs. After spawning, the female looks after the eggs and the male defends the territory. Hatching takes place after 3-4 days. Parents transfer the larvae to a hole dug in the substrate. After the next 6-8 days, young people begin to swim independently and distance themselves more and more from their parents.

During this period, they should be given small food, such as brine shrimp or mosquito larvae. It is not advisable to separate them from their parents for at least 6 weeks.


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