More as 100 species of the Genus Clarias have been described in Africa. Until the early 80's five species for the subgenus Clarias were recognized in Africa;
In 1982 Teugels revised the subgenus Clarias and found only two species (C. gariepinus and C. anguillaris) if the number of gill rakers on the first branchial arch is considered. For C. anguillaris the number of gillrakers is rather low (14 to 40) while the number of gill rakers for C. gariepinus is rather high (20 to 100, see figure 1.).
Figure Regression lines showing the correlation between standard length and number of gill-rakers on the first branchial arch for the catfish species of the subgenus Clarias (Clarias) recognized by Boulanger (1911) and David (1935), (After Teugels, 1982b).
It should however be realized that this division is based on morphological criteria (the number of gill rakers). A comparison of the feeding habits, piscivorous behaviour and reproduction patterns of C. gariepinus of several locations in Africa indicated some remarkable differences (de Graaf et. al. in press, Annex II). Therefore it could be of importance also to know what is the “old species name” name of the used catfish.