Effects of paddy straw and sugarcane bagasse on water quality,bacterial biofilm production and growth and survival of rohu, Labeorohita (Hamilton)

摘要

Sugarcane bagasse (T sub(1)), paddy straw (T sub(2)) and their mixture (T sub(3)) were added to mud-bottomed, manured cement tanks in triplicate to study the effect on bacterial biofilm production and growth and survival of rohu, Labeo rohita. All tanks were stocked with fingerling rohu at 10 000 ha super(-1). The total plate count (TPC) of bacteria in water and on substrate did not differ significantly between treatments. The mean phytoplankton and zooplankton density in water was the highest in T sub(2), followed by T sub(3) and T sub(1). The growth of fish was significantly (P0.05) higher in T sub(2) and T sub(3) compared with T sub(1). Significantly higher RNA values were recorded in T sub(2) and T sub(3) compared with T sub(1). Similarly, T sub(2) and T sub(3) registered higher DNA values than T sub(1). RNA:DNA ratio was higher in T sub(2) compared with T sub(1). However, T sub(3) did not differ significantly from T sub(1) and T sub(2). Both intestinal and hepatopancreatic protease and lipase activity was higher in T sub(1) and T sub(2) compared with T sub(3) and both differ significantly from T sub(1). Intestinal amylase activity was higher in T sub(2) and T sub(3) compared with T sub(1), whereas hepatopancreatic amylase activity was higher in T sub(2) compared with T sub(1) and T sub(3). The results demonstrated that production of L. rohita can be significantly increased by the introduction of biodegradable substrates into culture systems where fertilization is employed.