Morphological variations, length-weight relationships and condition factors of Hemichromis camerounensis (Cichliformes, Cichlidae) in three lakes in northern Cameroon

Abstract

The presence of numerous crater lakes in the Cameroon Volcanic Line offers an exceptional opportunity to study the influence of habitat on the evolution of cichlids. We examined the characteristics of three lake populations of Hemichromis camerounensis, all located on the Adamawa plateau in northern Cameroon. In total, 31 morphometric characters were examined of 277 fish specimens caught in two lakes with an outlet (Dang and Bini) and in a lake without an outlet (Tizong). Length-weight relationships and condition factors were estimated for each population. The physico-chemical parameters of the water were measured. Lake Tizong differed significantly from the other two lakes by its higher values of pH, conductivity and TDS. The length/depth and height/width ratios of different parts of the body and the total number of gill rakers on the first gill arch were significantly reduced in the population of Tizong, which was also characterized by small size individuals. The length-weight relationship was positively allometric for the populations of Bini and Dang but negatively allometric for the population of Lake Tizong. The condition factor of the fish was very low in Tizong. The morphological differences observed between the three populations should be taken into account in any systematic study that includes H. camerounensis populations from the studied zone.