THE EFFECT OF EARLY WEANING DIET AND FEEDING METHOD ON SURVIVAL AND LONGEST WEANING PERIOD FOR ELVERS STAGE OF EUROPEAN EEL, Anguilla Anguilla

Weaning period is the most critical period of eel life stages where high mortality rate (30-70%) occurred during the first three month after capture and it is one of the main obstacles facing eel culture as a consequence to transfer into a suitable artificial diet. The information on how the early waning diet and  suitable feeding methods effects on the elvers feeding behavior weaning process in terms of weaning time and survival rates is lacking. Therefore, two experiments were conducted to evaluate the effect of three early weaning diets (liver (BL), worms (Tubifex spp., TW) and mixed of (50%BL+50%TW)) and four different feeding methods (aquarium bottom method (ABM), floating net method (FNM), rubber pipe method (RPM Fig.1) and feeding chamber method (FCM, Fig.2)) on survival rate, longest weaning period, suitable feeding method that decrease feed loses and improve water quality for elvers stage of European eel, Anguilla anguilla.

Elvers responded differently to early weaning diets (BL, TW and BL+ TW) in terms of feed intake, survival rate and weaning period. Higher feed intake of early weaning diet recorded for fish fed TW followed by fish fed BL+TW, while, the lowest value noticed for BL treatment. Survival rate followed the same trend. Results suggested that 42 days was needed to wean elver fed on TW diet. However, delivering weaning diet using aquarium bottom method (ABM) resulted in the highest feed loses, while the lowest   value recorded for feeding chamber method (FCM). Feeding elvers using (FCM) recorded the highest real feed intake and survival rate compared to other feeding methods. Results indicate that for elvers stage of European eel, Anguilla anguilla feeding method defiantly play the major role in decreasing feed loses and in sequent improve water quality and survival rate. Worms (Tubifex spp.) as early weaning diet is the most convenient for elvers feeding as recorded the highest survival rate, the longest weaning period and lowest feed loses.