A new species of Cyprichromis cichlid has been described from the Zambian coast of Lake Tanganyika in East Africa.
The new fish, which has been named Cyprichromis coloratus, has just been described by Takahashi and Hori of Kyoto University in a paper in the latest issue of the Journal of Fish Biology.
The fish was discovered at Wonzye Point in Kasenga and Nkumbula Island in Zambia above a rocky bottom at depths of 7-12m/23-40 feet, but also occurs in deeper waters.
Like many of the Cyprichromis species, it exists in several colour morphs including a purple-tailed and yellow-tailed variety - which is where its common name is derived from. Both male colour traits occur within the same population.
The authors state that the fish is found exclusively in deep water over a rocky bottom and females and sub-adult males form schools consisting of tens or hundreds of individuals. The schools do not exclusively contain a single Cyprichromis species. In shallower waters of only a few metres deep, Cyprichromis coloratus schools with leptosoma, but at depths of around 15m the fish is seen alongside C. zonatus, C. leptosoma and Paracyprichromis brieni.
In very deep water of around 25m, the other species are replaced by C. pavo and P. nigripinnis. The mixed species shoals are said to be several metres wide and split and reform frequently roaming over areas of 150-250m where they feed upon zooplankton in the water column.
The new discovery brings the total number of described species in the genus to five: C. microlepidotus, C. leptosoma, C. pavo, C. zonatus and C. coloratus. The authors have provided a new dichotomous key for the genus to allow people to identify the fishes to species level.
Unlike Cyprichromis pavo, microlepidotus and zonatus, C. coloratus lacks small spots on the body and exhibits dichromatism in male tail colour within the same population.
C. coloratus also has more spinous rays in the dorsal fin than some species, with 14-15, rather than the 11-13 seen in leptosoma.
The new species also shows sexual dimorphism with females having much larger heads than males - Cyprichromis are maternal mouthbrooders and hold very large fry - and males having longer pelvic fins.
Males are said to hold territories above rocks and form a lek-like system in water of 8-30m deep. Like the territories of marine Anthias, Cyprichromis coloratus maintains its territory across three dimensions and defends from above, below and all sides.
The spawning behaviour of the species has not yet been observed, but the authors believe it is likely to be similar to that of C. leptosoma, which spawns in midwater. The mouthbrooding females school together and release small numbers of fry (typically 11 to 16) after several weeks of brooding.
Takahashi told Practical Fishkeeping that the new species is available in the aquarium trade and that he is aware of some variations within the Cyprichromis genus that could be potential new species:
"I think some detailed morphological and genetic studies are required to determine which variants are undescribed species and which variantion is local variation in a described species."
Takahashi, Hori and Nakaya described the fourth Cyprichromis, C. zonatus, back in 2002, but are perhaps best known for their work on splitting Cyphotilapia into two species - frontosa and gibberosa. The fish is a member of the Cyprichromini tribe of cichlids which are endemic to Lake Tanganyika and live and spawn in open water.
For more information on the new species see the paper: Takahashi T and M Hori (2006) - Description of a new Lake Tanganyikan cichlid fish from the genus Cyprichromis (Perciformes: Cichlidae) with a note on sexual dimorphism. Journal of Fish Biology (2006) 68 supplement B; 174-192.