On-farm evaluation of Indian major carp production with sugarcane bagasse as substrate for periphyton

摘要

To study the effect of sugarcane bagasse as an artificial substrate for periphyton in fish ponds, an on-farm polyculture experiment was carried out, stocking catla (Catla catla), rohu (Labeo rohita) and common carp (Cyprinus carpio) in an 800 m~2 earthen pond partitioned into eight 100 m~2 compartments with fine meshed nylon netting. Fifty catla and 25 each of common carp and rohu were stocked per compartment and grown for 180 days. Sugarcane bagasse bundles (length 80 cm, diameter 3.3 cm) at densities of 0, 39, 78 and 156 (or 0, 7.0, 13.7 and 28.2 kg 100 m~(-2)) were hung in two compartments each as a substrate. Supplemental feed (a 1:1 mixture of groundnut cake and rice bran) was provided in one replicate of each substrate density at a rate of 5percent body weight during the first half and 3 percent throughout the second half of the experiment. Water quality and periphyton biomass were monitored at fortnightly and monthly intervals, respectively. Bagasse substrate did not adversely affect water quality, dissolved oxygen levels being between 4 and 13 mg centre dot l~(-1) throughout the experiment. Only minor differences in periphyton and plankton density were observed between treatments. Marked differences were recorded in fish production. Total fish production of 8076 g centre dot 100 m~(-2) was obtained without feed and periphyton (control). Feeding alone increased yield compared to controls by 20 percent. Bagasse substrate alone increased yields by 38, 61 and 62 percent in the 39, 78 and 156 bagasse bundles per 100 m~(-2) treatments, respectively, while the combination of feeding and periphyton resulted in 45, 67 and 84 percent increases in yield in the 39, 78 and 156 bagasse bundles per 100 m~(-2) treatments, respectively. Regression analysis predicted that maximum total fish production would be achieved at bagasse densities of 117 bundles (21 kg) per 100 m~2 without feeding and 156 bundles (28 kg) per 100 m~2 with feeding. The results demonstrate that sugarcane bagasse can be successfully used as a substrate for periphyton. Further research is needed to assess the practical and economic feasibility of periphyton-based aquaculture in India.