Jack Dempseys are a species of tropical fish belonging to the large and varied cichlid family. They are native to southern Mexico and Central American and favor murky, slow-moving waters with a sandy substrate. Their name comes from the American heavyweight boxing champion Jack Dempsey and is an indication of their aggressive and energetic nature. Except for its aggressive nature, it is a hardy and easy-to-care-for tropical fish.
Size and Tank Requirements
Young Dempseys sold in tropical fish stores are usually only a few inches long. This can be deceiving for an inexperienced aquarist because the adult can reach a size of 10 inches. Recommended tank size for a single adult Dempsey is approximately 55 gallons and 75 gallons for a pair. The addition of other species will affect the tank size needed as well. Crowding increases the Dempseys' aggressiveness.
Dempseys in a Community Tank
The Jack Dempsey cichlid is not a good fish to be kept in a general community tank. They are an attractive fish and often sold when young and small, but will quickly grow and dominate most community tank fish that are generally more peaceful than the Dempsey. As a rule, they will eat any fish they can fit in their mouths and they become more aggressive with age.
Keeping Multiple Dempseys
Multiple Jack Dempseys kept in the same aquarium will need plenty of room and rocks and plants to use as hiding places and to serve as territorial boundaries. Dempseys are very territorial and also size-conscious, so multiple fish in the same tank should be of the same size. Aggression increases during mating and a mating pair should be kept by themselves.
Keeping Other Species with Jack Dempseys
Some large species can be kept with Dempseys, but it is best to introduce the Dempsey to the tank after the other fish. If fish are added after the Dempsey, it will see these as invaders of its territory and become very aggressive. Other large, aggressive South American cichlids can make good tankmates. Oscars can co-exist with Dempseys if given enough room. Some non-cichlid species that can live with Dempseys are large tinfoil barbs, bala sharks and large catfish or plecos. The aquarium should have enough room to give these fish space to thrive.