Nursery rearing of rohu Labeo rohita (Hamilton, 1822) using water lettuce (Pistia stratiotes) compost

Efficacy of water lettuce (Pistia stratiotes) compost in pond fertilisation and nursery rearing of the Indian major carp, Labeo rohita (Hamilton, 1822) was assessed at doses of 0.5, 1.0 and 1.5 kg m-3 with an aim of eco-friendly management of this weed. Half of the compost prepared by anaerobic digestion was applied 7 days before stocking the spawn of rohu and the rest half was applied after 15 days of stocking. The stocking density of spawn was 100 nos. m-3 and duration of the study was 30 days. No feed was supplemented during the entire nursery rearing period. The basic water and soil quality parameters of the ponds were analysed on 0, 15 and 30th day of stocking which showed a slight increase in pH, total alkalinity and ammonia (p<0.05) and a decrease in dissolved oxygen of water with increase in compost doses. Plankton density was highest when compost application was @ 1.0 kg m-3 and it was lowest when compost application was @ 1.5 kg m-3. Soil pH (p???0.05), organic carbon, available nitrogen and phosphorus (p<0.05) were increased with increase in compost doses. The growth and survival of fish, fish production and profit were highest (p<0.05) when the compost was applied at a dose of 1 kg m-3. From the results of the study, it is concluded that water lettuce can be used as a compost for pond fertilisation and rohu seed production.