Impact on environment intervention of carps-sis polyculture in north-west of Bangladesh

Abstract

This study was carried out in different water bodies to assess production potentials on carp-mola polyculture commonly found from July-December 2012. Pond and pond like inundated rice plots were employed for the experiment. It was comprised of three treatments with having 12 replicate in two districts. The examined species: rohu (Labeo rohita), catla (Catla catla), mrigal (Cirrhinus cirrhosus), silver carp (Hypophthalmichthys molitrix), silver barb (Barbodes gonionotus), bata (Labeo bata) and mola (Amblypharyngodon mola) were stocked in both pond and rice field. The two treatments were utilized by ricefields with carps-mola (T1-RCM) and only carps (T3-RC) and other treatment by ponds with carps-mola (T3-PCM). The stocking rate of all carps were 20/dec. in all rice plots of two treatments (T1 & T3) but in ponds 40/dec. Whereas, mola stocked same rate (150g/dec.) of all treatment. Five important water quality parameters were measured monthly interval. Temperature, pH and alkalinity were significantly differences but transparency and DO were not varied significantly among all the treatments. The gross production of fishes was the highest (3157.96 kg ha-1) in T2 where carp-mola polyculture represent in ponds with double stocking rate of carps from ricefield. But among the all carps species were the highest harvesting weight in ricefields. And also from the total production of mola was the highest (20%) in T1 between Ricefield (T1) and ponds (T2) treatments. Subsequently, other SIS production was the highest in T3 treatment where not stocked small fish. As higher production and their high market value of mola boost up the BCR (3.43) in T1 among all treatments. Hence, it is summarized that pond like alternate rice plot are more abundance of natural food which enhance the production both carps and mola as well.