Q. I would like to know about the care and breeding of the Jack Dempsey fish. This cichlid fish is very popular in my area, yet I get contradictory advice on its care and breeding.
A. Heros octofasciatus, to give the Jack Dempsey its scientific name, is native to the Atlantic slope of Middle America. It can be found from the Rio Ulua in Honduras northwards to the Rio Paso San Juan in southeastern Mexico. Most cichlid fish enthusiasts regard the Dempsey as a mid-sized representative of its genus. I have seen specimens close to 12 inches overall length, but a male of 8 inches total length would be considered large by most aquarists. Females are usually a few inches smaller.
This handsome cichlid fish prefers moderately hard water (up to 100 parts per million total dissolved solids) and pH values of 7.2 to 7.6. It looks best when kept under such conditions, but like most Central American cichlid fish, the Dempsey is adaptable enough in this regard to prosper over a wide range of water conditions as long as extremes of pH or hardness are avoided. A temperature range of 70 to 75 degrees Fahrenheit suffices for day-to-day maintenance, with an increase to 80 to 83 degrees Fahrenheit for breeding. Like all cichlid fish, Heros octofasciatus is less aggressive and thus more easily managed at the low end of its preferred temperature range. In nature, Dempseys feed upon aquatic invertebrates, including snails, and small fish. Such items are obviously appreciated in captivity, but this species will enthusiastically consume prepared and frozen fish foods and can be expected to prosper on such a diet.
Heros octofasciatus demolishes rooted aquatic plants and digs prodigiously. Aquascape its aquarium accordingly. Always base rockwork solidly on the aquarium bottom, never on the surface of the gravel, and limit vegetation to a layer of floating aquatic plants.
Single specimens get along well other Middle American cichlid fish. I have even seen them kept successfully with such South American genera as Aequidens, Cichlasoma, Geophagus and Satanoperca. Do not try to keep a pair of Heros octofasciatus under community conditions in an aquarium less than 6 feet long. Sexually active Dempseys defend their breeding territory aggressively. This behavior can have lethal consequences for tankmates unable to move beyond the limits of the couple’s domain. Large, fast-moving, midwater-swimming tankmates such as silver dollars or tinfoil barbs are usually safe from the attentions of non-breeding Dempseys. So are aggressive smooth-skinned catfishes such as the numerous Synodontis catfish species and their heavily armored cousins of the family Loricariidae. However, such tolerance ends once a pair decides to spawn!
To obtain a compatible pair of these cichlid fish with minimal difficulty, raise a group of six to eight youngsters to maturity together. The first two fish to pair off will make life interesting for their tankmates, who must be moved elsewhere if the aquarium is too small to allow them to move beyond the honeymooners’ reach. Dempseys place their eggs on a pre-cleaned surface. An enclosed spawning site seems preferred — large clay flowerpots set on their sides are readily accepted in captivity.
The female does most spawn tending, while her mate keeps intruders a safe distance from the developing eggs. The fry hatch in three days at 82 degrees Fahrenheit and are fully mobile four days later. Offer them newly hatched brine shrimp or finely powdered prepared fish foods for their initial meal. If fed several times daily and kept under a regime of frequent partial water changes, the hardy young grow rapidly. Because Dempsey parents are as prolific as they are diligent, few aquarists have the space to rear an entire brood of fry to independence. To avoid overcrowding and all the problems that go with it, emulate natural predation by siphoning out 50 to 75 percent of the wrigglers for use as live fish food, and allow the parents to concentrate on caring for the remaining fry.