Length-weight relationships and condition factors of Mochokidae (Pisces: Teleostei: Siluriformes) from Niger River, Northern Benin

Abstract

In the Niger River in Benin, the fishes of Mochokidae family are of high commercial and economic importance. The current study investigated size structures, length-weight relationships and condition factors of these catfishes in order to evaluate their plumpness. Mochokids were sampled monthly from February 2015 to July 2016 with traps, seine and gillnet. Overall, the fish species showed unimodal, bimodal and tri-modal standard-length distributions. Length-weight models displayed allometric coefficients (b) varying between 2.236 and 3.380, indicating positive and negative allometric growth with correlation coefficients (r) ranging between 0.87 and 0.99. Condition factors were moderate to low and varied from K= 0.409 for Synodontis frontosus to K= 7.276 for Synodontis sorex that showed a higher value K= 31.13 in aquatic vegetation. Major threats were the use of chemical fertilizers and pesticides for adjacent agriculture, the retrieval of water for agriculture and domestic uses, the invasion of floating plants, the introduction of exotic fish species and overfishing. These data constitute valuable fisheries documentation that will contribute to conservation, valorization and sustainable exploitation of Mochokid fishes in Niger River in Benin.