Utilization of unused Nutrients in an aquaculture Production System

Abstract

Morning glory (Ipomoea reptans) and taro (Colocasia esculenta) were produced in a recirculating aquaculture system of monosex GIFT tilapia (GIFT, Oreochromis niloticus, L.) for a period of 15 weeks. Tilapia fry of uniform size of 0.76 g were released in three treatments (stocking densities): 106fish/m3 (T1), 142fish/m3 (T2) and 177fish/m3 (T3) to assess the effect of stocking density on the production of vegetables. Fish were fed with commercial feed containing 25% protein. The production of morning glory in different treatments ranged between 2642.53 to 2782.11g and the average production was 2500 g/m2 . The production of taro in the three treatments varied from 1913.52 to 1979.85g and the average production was 1800 g/m2 . Stocking density of fish had no significant influence on the production of morning glory and taro. In order to utilize the remaining nutrients, amaranth (Amaranthus cannabinus) was produced using a mixture of normal soil and sun-dried bottom sediment at a ratio of 5:1. A control system was maintained to compare the production performance. The germination rate and production of amaranth was significantly different in the two treatments. Production of amaranth with the mixture of normal soil and bottom sediment was 36.36 times higher than the production with normal soil. The result indicated the nutrient richness and fertility of the bottom sediment