Q. Two years ago I purchased two types of cichlids I had never encountered before. At this club auctions one rather large specimen, which looked fully grown to me, was tagged as Archocentrus centrarchus. The other lot contained seven small fry labeled Theraps nicaraguensis. I raised the fry to about an inch in length, kept two and sold the remaining five at the next club auction. One of the two I kept grew to nearly 7 inches in length in just a few months' time. The other never grew larger than 3 inches. Both share a 55-gallon tank with the A. centrarchus.

I have not been able to find information on either species, which I believe have been renamed. My guess is that the T. nicaraguensis are some type of Hypselacara, while the A. centrarchus is some type of native sunfish. Any information you can supply on these fish would be helpful.

A. Your suspicion of name changes is well founded. Both species made their aquarium debut as Cichlasoma species. You might possibly have found information on these fish by looking under Cichlasoma centrarchus or C. nicaraguense.

Your suggestion that A. centrarchus is actually a North American sunfish, while perceptive, is still in error. This species is a cichlid native to the Atlantic slope rivers of Nicaragua and Costa Rica. Its superficial resemblance to one of our native sunfishes, the flier (Centrarchus macropterus), is commemorated in the specific epithet centrarchus, bestowed upon it by Theodore Gill and J. F. Bransford when they formally described it in 1877.

This is the largest representative of the genus Archocentrus, growing to 6 inches standard length (SL) in captivity. It tends to behave aggressively toward others of its own species, but can be expected to get along well with other cichlids and non-cichlid tankmates too large to make a convenient mouthful. An omnivore in nature, it will readily accept any of the usually available live, frozen and prepared foods.

Like the generality of Middle American cichlids, it prefers neutral to slightly alkaline, moderately hard water. Archocentrus centrarchus is moderately sensitive to dissolved metabolic wastes and does best under a regimen of frequent partial water changes.

Should you decide to breed this species, you will find that the main features of its reproductive pattern do not differ significantly from those of the most frequently kept representative of the genus, Archocentrus nigrofasciatus. Sexual dimorphism in this species is less marked than in the convict cichlid, however. Males have somewhat longer and more pointed soft dorsal and anal fins than do females, and usually display more metallic green coloration on the flanks.

Theraps nicaraguensis is a relatively slender-bodied species whose distribution overlaps that of A. centrarchus. Omnivorous, with strong herbivorous tendencies, it is a rather aberrant representative of its genus, living over open sandy bottoms and sifting through the substrate in search of food.

As you have already discovered, this species displays significant sexual dimorphism. Males grow about twice as large as females and have much longer soft dorsal and anal fins. Females, while smaller than their consorts, are blessed with a metallic orange-red shoulder patch and an iridescent blue-green spiny dorsal fin.

Like its distant relative A. centrarchus, this species behaves more aggressively toward conspecifics than toward other fish species. Its predatory tendencies are very poorly developed, making it a satisfactory companion for a wide selection of mid-water dwelling non-cichlid tankmates. Its management requirements are essentially identical to those of the preceding species, but its greater sensitivity to dissolved metabolites dictate rigorous adherence to a frequent schedule of partial water changes if it is to prosper in your aquarium.

This species has a reputation for being difficult to breed in captivity. Problems usually arise when T. nicaraguensis is housed with more assertive tankmates that prevent a pair from establishing a breeding territory. Moving the prospective breeders into the company of less aggressive companions will usually resolve this difficulty. It is also worth noting that courtship in this species is protracted, and seems to include multiple false spawnings.

Like most Middle American cichlids, T. nicaraguensis is a monogamous substrate spawner that practices long-term care of its free-swimming young. Unlike the generality of substrate-spawning cichlids, which attach their adhesive eggs on a pre-cleaned solid surface, this species deposits non-adhesive eggs at the bottom of a deep pit. Because excavation of a spawning site appears to play an important role in the process of pair formation, it is important to afford captive fish comparable opportunities in captivity. Burying a 12- to 15-inch length of 4-inch diameter PVC or ceramic pipe to a depth of 3 inches will provide a prospective pair of T. nicaraguensis ample opportunity to exercise their talents in an appropriate manner.

A pair can produce up to 1000 ovoid, beige eggs. It is not unusual for a pair to eat their first few clutches. The exercise of a bit of patience will see them settle down to responsible and highly competent parenthood. Both parents share in hygienic behavior, which seems rather poorly developed by comparison with that of other cichlasomines.

The eggs hatch 72 hours postspawning at a temperature of 79 to 80 degrees Fahrenheit. The wrigglers are then moved by their parents to pits previously dug by their father. They swim freely four days after hatching and have no trouble consuming newly hatched brine shrimp and finely powdered prepared foods. The growing fry are sensitive to dissolved metabolic wastes. However, if due attention is paid to nitrogen cycle management in their aquarium, rearing them is a straightforward proposition.

The young begin to develop their attractive adult coloration some eight to 10 months postspawning at 4 inches total length for males, and slightly less for females. The onset of reproductive behavior follows shortly thereafter, but it may take another year for young T. nicaraguensis to develop the full potential of their color pattern and attain reproductive competence. Good luck with your cichlids.