Growth and fatty acid composition of Nile tilapia Oreochromis niloticus L. fed Azolla-diets, in tanks and in earthen ponds: A comparative study

Two 90-day experiments were conducted in the same period in tanks and in earthen ponds to study the effects of culture systems on growth and fatty acid (FA) of Nile tilapia (Oreochromis niloticus L.) fingerlings (mean weight: 16.3 g) fed Azolla, as partial replacement for fish meal (FM). Diets were isonitrogenous (29.2 % CP) and iso-energetic (16.9 kJ·g−1) containing 0 % (A0), 10% (A10), 20 % (A20), 30 % (A30), 40 % (A40) and 50% (A50) of Azolla meal (AM) respectively. Diet A0, without AM, acted as a control. In both experi-ments, fish growth decreased as AM level in-creased in diets (P < 0.05), and values were sig-nificantly higher (P < 0.001) in ponds than i