This week, we adopted a new fish for our aquarium: a half-grown Jack Dempsey cichlid (pronounced “sick-lid”). This 6-inch bruiser was previously in a larger tank where he was harassing an assortment of goldfish and koi. Now he has a tank all to himself, where he won’t have to share the space with any other fish.
While this may seem mean to some, this is actually typical behavior for Jack Dempseys and most other fish in the cichlid family. These fish are territorial by nature, and will actively defend their living space against all other fish. In fact, that is how this particular species got its common label; it is named after the famous 1920’s boxer William “Jack” Dempsey, because of its notable aggression and tenacity. Some even say the fish bears a strong likeness to the boxer’s defined facial features!
However, despite their reputation for ferocity, Jack Dempseys and most other cichlids are among the best parents on the fish world. A male and female will form a strong bond, and may remain together for several years. Cichlids are among the few groups of fish that form nuclear families; i.e. a monogamous pair with offspring. One reason they make such great moms and dads is that they will aggressively defend their young just as fervently as they defend their territory.
Jack Dempseys hail from Central & South American waterways, preferring slow-moving water & bogs. They like warm water in the mid-70s and a pH between 6.0-7.5, although if acclimated slowly, they adapt well enough to most water parameters. They are among the larger members of the cichlid family, averaging around 10 to 12 inches in length. Jacks are predatory by nature, eating virtually any critters they can gulp into their sizable jaws, including smaller fish, crustaceans, worms, and other invertebrates.
In addition to their tenacious personality, many aquarists are drawn to Jack Dempseys because of their vibrant green and blue coloration, especially in mature specimens. The emerald scalation of a grown Jack glimmers in a clean aquarium like a living jewel.
Overall, if you have a large, aquarium with plenty of filtration, and you are looking for a sizable, predatory fish with some nice color and a lot of personality, the Jack Dempsey cichlid would be a great candidate.