Diet, ontogenetic changes and rhythm of feeding activities in Macrobrachium macrobrachion (Herklots, 1851) (Decapoda, Palaemonidae) in the waterbodies and rivers of Benin, West Africa

Abstract

Abstract Knowledge of the diet of Macrobrachium macrobrachion (Herklots, 1851) in its natural environment is a key factor facilitating its successful breeding. We have analysed the stomach content of 452 specimens collected from the Ouémé River Delta (ORD) (338 stomachs) and from the Mono River/Grand-Popo Lagoon complex (MGLC) (114 stomachs), from February to October 2016. The analysis enables to calculate the coefficient of vacuity for the ORD (3.50%) and for the MGLC (3.50%). The results show that M. macrobrachion has a detritivore-omnivore type of diet, feeding mainly on phytoplankton (diatoms and cyanophytes) and detritus. However, the diet of the young shrimps, composed mostly of insect larvae, differs from that of adult. In the adult M. macrobrachion, the pace of feeding activities is greatest in the morning (6.00 to 9.00 am), low in middle of the day (10.00 am to 13.00 pm), and there is a slight trophic activity between 17.00 and 22.00 pm. Outside of the above periods, i.e., from 14.00 to 16.00 pm and 23.00 pm to 5.00 am, the species is at rest. Juveniles feed at dawn. In the nighttime and at dusk, groups of shrimps of varying sizes do feed. The findings of this study suggest that live prey is the best feed for the larvae of M. macrobrachion in captivity and should be distributed preferably early in the morning.