DIGESTIBILITY AND PERFORMANCE OF WATER HYACINTH MEAL IN THE DIETS OF Clarias gariepinus (BURCHELL, 1822).

Abstract

Water hyacinth meal (WHM) as an alternative protein source was investigated in this study. Whole water hyacinth plant meal (WPM), water hyacinth leaf meal (WLM) and soya bean meal (SBM) were used to compound three isoproteic (40% crude protein) fish diets. Catfish of 11.2 ± 0.3g average weight were used for the 70-day digestibility study. Data were collected forthnightly on fish growth performance and water qualities (dissolved oxygen, pH, ammonia and temperature). Fish, feeds, and faecal wastes were analyzed. Fish fed SBM-based diet had superior performance over those fed WHM-based diets with respect to Mean weight gain (MWG), Specific growth rate (SGR), Protein efficiency ratio (PER), Feed conversion ratio (FCR), Nitrogen metabolism (Nm) and digestibility coefficients (ADC).  Fish fed all diets exhibited marginal difference in total feed intake but growth performance and nutrient utilization were significantly higher in fish fed WLM than fish fed WPM probably as a result of high fibre content present in WPM. Extremely low value of ammonia was recorded in water under WPM treatment (0.18±0.06 mg/l) while water under WLM and SBM treatment had significantly higher values of ammonia 0.46± 0.13 mg/l and 0.71± 0.10 mg/l respectively. These observations may be due to the presence of significantly higher fibre content in the WPM than other meals. Consequently this could be responsible for its poor digestibility values but high potential for waste water purification. Water hyacinth leaf meal (WLM) would therefore serve a better option for adoption in ensuring maximum utilization potentials of the aquatic plant both for profitable and sustainable fish production.