Abstract
Catfishes belonging to the genus Chrysichthys are generally important fish species in inland water bodies of Africa because of their high commercial value. Among them, C. nigrodigitatus could represent, at certain periods of the year the highest biomass of the littoral ichthyofauna, accounting for 17 to 43.8% of total catches. In this paper, its diet in the hydrosystem Lake Togo-Lagoon of Aného was investigated focusing on how differences in diet and food consumption are related to size, season and sexual maturity. A total of 195 males and 137 females were sampled from January to December 2017. The digestive tract of each individual was dissected and its content was analyzed, using indexes of stomach contents analysis method. Diet variability in relation to season and biometric parameters was also studied. About 99 stomachs were empty with an overall vacuity index of 29.82%. However, vacuity index was found to vary in relation to fish size and months. The fish has been found to be omnivorous with a carnivorous tendency consuming a wide range of prey items (H = 3.34). Juvenile and adult freshwater clams (Galatea paradoxa) were the numerical dominant preys (%N = 44%) while the penaeid shrimps (Farfantepenaeus notialis) with an annual frequency of occurrence (Fo) of 49.36% and all species confused of fish (33.91%) were the most preferred preys. The index of relative importance (IRI) reveals that freshwater clam (40.49%), penaeid shrimps (35.85%) and all species confused of fish (14.58%) were the most important preys of C. nigrodigitatus. The dominance of Malacostraca and Mollusca in the diet of C. nigrodigitatus in the hydrosystem Lake Togo-Lagoon of Aného is likely one of the more important considerations for future management plans.
Highlights
Fish and seafood are highly valued and play an important role in human diet because of their content of high quality protein and essential amino acids, polyunsaturated fatty acids and micronutrients [1]
The present study aims to characterize the diet of C. nigrodigitatus from the hydrosystem Lake Togo-Lagoon of Aného through a qualitative and quantitative description of the stomach contents and its temporal and ontogenetic variation
The results indicated that clams G. paradoxa (40.49%) and shrimps F. notialis (35.85%) which together make up 76.34% of the index of relative importance (IRI) are the most important and preferred preys of C. nigrodigitatus
Summary
Fish and seafood are highly valued and play an important role in human diet because of their content of high quality protein and essential amino acids, polyunsaturated fatty acids and micronutrients [1]. In 2017, according to FAO estimates, fish provided at least 50% of the total animal protein intake of humans in several West African countries including Togo [2] In these countries, artisanal catches could represent the bulk (60%) of the domestic fisheries catches [3]. Total catches of many valued food fishes (silver catfish, blackchin tilapia...) have decreased because of overfishing, drought and watershed degradation [3] [6] It was strongly recommended that the necessary efforts be made to achieve a rational management of the stock and to find ways of improving the level of productivity of coastal lagoons and estuaries [5]
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