Morphology
P. polleni is a laterally compressed full-bodied fish. Like most cichlids it resembles a perch-type fish in shape, hence the taxonomic designation perciformes - 'perch-like'. Males in captivity will develop a nuchal hump, a layer of fat above the eyes, though not to the same degree as other similar African cichlids, such as the Cyphotilapia frontosa and Tilapias of Africa. Adult P. polleni, and sub-adult dominant individuals are jet black in color, covered with brilliant iridescent spots which shift from golden to blue depending on the movement of the fish and the angle of the light, the eye is a bright yellow. The male P. polleni can reach almost 30 cm (12 in) in length; females usually half that length. Sexing individuals thus becomes easier as they mature. In addition, males tend to have longer and sharper pelvic fins, and the edge of the dorsal and anal fins are often straighter in males, and more 'rounded' in females. Among aquarists it is often said that the females, though smaller are more beautiful in their coloration patterning. There are two color varieties of the P. polleni; the 'large spot' and the 'small spot'. Adults of both sexes display the strongest coloration during courtship and spawning. Among cichlid enthusiasts there is some confusion as to the names of these two varieties, with large spot individuals sometimes being erroneously referred to by the junior synonym P. bleekeri. Juveniles with a length of less than 3 cm (1 in) are dull brown.
Habitat and behavior
In the wild, P. polleni inhabits a number of rivers and associated streams in northern Madagascar, including the environs of the town of Andapa, where most individuals exported for the aquarium trade in recent years were collected. It is an omnivorous fish and occasional opportunistic piscivore, approaching smaller unsuspecting fish by stealth, with their dark coloration giving them an advantage. P. polleni observed hunting in the aquarium environment will sneak up on smaller fish from below during the pre-dawn hours and suck the smaller fish into their mouths using the typical cichlid 'suction effect' caused by quickly opening their mouths. Thus, using stealth and crypsis they are able to prey on fish they would otherwise not be able to catch. In Madagascar, P. polleni is a food fish, and like many cichlid fishes in many regions, reputed to have a good flavor.
In the aquarium
P. polleni is temperature and pH tolerant, and reasonably hardy and not shy. As such, this fish is an ideal aquarium fish if given the appropriate environment and tank mates for a medium sized aggressive cichlid. They eat most commercial fish foods, such as flakes, pellets, frozen, and alike. P. polleni displays the same kind of 'intelligent' behavior common to other cichlids. They can be trained to eat from the hand and will recognize and approach their owner (and often retreat from an unfamiliar person).
In the aquarium, P. polleni are more cautious and easily spooked than many of the more readily available cichlids, but otherwise adaptable to aquarium life. P. polleni is aggressive towards conspecifics, especially if a pair bond develops. The pair bond between males and females is sporadic and easily broken. If this happens the female can become imperiled by the male's aggression if not removed. Despite these qualities, P. polleni is not well known in the aquarium trade, though this is beginning to change. If they display full coloration, non-dominant and sub-dominant individuals of any size will often suffer aggression from the alpha individual(s). For this reason, there is generally only one or two fully colored individuals in an aquarium with many specimens. These traits may contribute to the relative obscurity of P. polleni in the hobby.
P. polleni rank among the more aggressive African cichlids, comparable to Malawi and Tilapia cichlids. Some individuals have been known to kill their tank mates upon reaching maturity, though as a rule P. polleni tolerates tankmates too large to eat fairly well. Successful aquarium spawnings are common.
