Raising of Stocking Materials of Indian Major Carps in Pen Enclosures in Selected Floodplain Wetlands of Assam, India

Abstract

Raised stocking materials, fingerling of Indian major carp seeds (Catla catla, Labeo rohita Cirrhinus mrigala) in pens, installed in two floodplain wetlands of Assam viz. Goruchora (Golaghat district) and 46-Morakollang (Morigaon district). The pens were stocked at 30,000 fry•ha-1, in a ratio of 3:2:1 of C. catla, L. rohita and C. mrigala fry, respectively. The average initial length and weight of fry at the time of stocking for C. catla, L. rohita and C. mrigala were 5.45 cm (1.80 g), 4.51 cm (1.15 g) and 4.65 cm (1.12 g), respectively. The fish stocks inside the pens were given supplementary feeds, mustard oil cake and rice polish (1:1) at 5% body weight. The pens were harvested after a rearing period of 145 days with an average growth of C. catla (19.0 cm, 85.1 g), L. rohita (15.8 cm, 52.8 g) and C. mrigala (15.8 cm, 42.9 g) in Goruchora wetland, while in 46- Morakollang wetland it was recorded as 17.0 cm (63.8 g) for C. catla, 15.4 cm (55.9 g) for L. rohita and 14.0 cm (41.5 g) for C. mrigala for further grow-out in the lakes proper. During the period of experimentation, the fluctuations in water quality parameters like water temperature (17.6-29.0o C), transparency (72-102 cm), dissolved oxygen (3.60-16.50 mg•l-1), pH (7.12-9.53), total dissolved solids (46.6-111.3 mg•l-1) and specific conductance (102-232 µS•cm-1) were monitored, too. The production in terms of fish biomass (fingerlings) was estimated at 2106 and 1780 kg•ha-1 in Goruchora and 46- Morakollang wetlands, respectively. The cost-benefit ratio was calculated as 1.40 (Goruchora) and 1.77 (46-Morakollang), which can be considered as significant, economically.