Effects of periphyton and mola (amblypharyngodon mold) on the production performance of mrigal (cirrhinus cirrhosus) and tilapia (oreochrdmis niloticus)

Abstract

Abstract : The experiment was conducted to compare the production performance of Mrigal (Cirrhinus cirrhosus) and Tilapia (Oreochromis niloticus) fish in polyculture systems for a period of 124 days in the ponds at the Fisheries Field Laboratory, Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh. The three treatments were: Mrigal and Tilapia without Mola (Amblypharyngodon mold) and periphyton (T,), Mrigal, Tilapia and Mola without periphyton (T2), and Mrigal, Tilapia and periphyton without Mola (T3), with three replications in each. The area of each pond was 140 m2 having water depth of 1.5m. The stocking density of Mrigal and Tilapia were 2,143 and 20,000 fingerlings ha'1, respectively in all treatments. Mola were stocked at 20,000 individuals ha1 in Mrigal, Tilapia and Mola treatment. The bamboo sticks (kanchi) were added as a substrate for periphyton growth Fertilizers like urea and triple super phosphate (TSP) were applied to the ponds at the rate of 50 kg ha1 at 30 days intervals throughout the cultured period. Fish were fed with supplemental feed twice daily at a rate of 3-5% of the body weight. Periphyton biomass grew on substrate at a higher rate in early months and decreased gradually till the end of the experiment. Mean values of the water quality parameters and benthic production showed no significant differences (PD0.05) among the treatments. Plankton abundance was significantly different (PO.05) among the treatments and the highest value were observed in T, (52.61±3.09 xlO3 individual l*1). The net production of 1686.74 kg ha'1 fish in T3 was higher than that of 1226.55 kg ha'1 (excluding Mola) and 1262.19 kg ha'1 (including Mola) andT, (1,233.29 kg