Productivity of Indian Major Carps in a Periphyton Based Aquaculture System

Abstract

The efficacy of two low cost substrates viz., rice straw and sugarcane bagasse was evaluated in a periphyton-based semi-intensive carp polyculture system through 120 days growth trial in 80 m2 outdoor cemented tanks manured with biogas slurry @ 20, 000 L/ha/yr and stocked with catla, rohu, mrigal and common carp @ 10, 000 fry/ha where treatment without any substrate served as control. The fish were fed with formulated supplementary diet (rice bran and mustard meal in 1: 1 ratio @ 10, 5 and 1.5% of its body weight (BW) for the first, second and the following months, respectively. The water quality and plankton (phytoplankton and zooplankton) production were similar in all the treatments. Chlorophyceae was the dominant group followed by cyanophyceae, bacillariophyceae and euglenophyceae among the phytoplankton while rotifers and crustaceans (copepods and cladocerans) dominated among the zooplankton in both the substrate treatments. Though higher (P<0.05) periphyton DM per unit area was recorded in rice straw substrate but periphyton ash and ash free DM content was similar in both the substrates. Growth response of fish to both the substrates varied with species. Catla, rohu and common carp attained higher (P<0.05) final BW (66.0±1.20, 39.20±1.13 and 167.10±4.80 g, respectively) with sugarcane bagasse substrate as compared to control group (54.90±1.89, 33.70±0.63 and 137.90±6.38 g, respectively) reared in tanks without any substrate. However, use of rice straw as substrate showed higher (P<0.05) final body weight was recorded only in case of common carp (165.40±4.76 g). Flesh quality of fish also appeared to vary with species in different treatments. Among all the species, a higher (P<0.05) total protein and ash content (on wet basis) was found in case of rohu with both rice straw (13.90±0.48% and 1.40±0.04%, respectively) and sugarcane bagasse (13.57±0.45 and 1.31±0.07%, respectively) substrates as compared to control (11.62±0.17 and 0.94±0.09%, respectively). This study revealed potential of using sugarcane bagasse as periphytic substrate in carp culture.