WATER QUALITY ASSESSMENT OF TILAPIA FARMING: A CASE STUDY OF NURSERY AND GROW-OUT POND

Abstract

An experiment was conducted to observe the water quality of tilapia farming. For the purpose of the study, two types of farming practices were selected viz. nursery and growout of tilapia farming in Kaharole Upazilla under Dinajpur district. Three nursery and three grow-out ponds from “Hye Hatchery” in Dinajpur district were selected for conducting the experiment. Water sampling from grow out ponds were started for a period of 6 months from April 2016 to September 2016. On the other hand, water samples from nursery ponds were collected for a period of 2 months from November to December, 2016. Among different water quality parameters only water level and temperature of nursery ponds varied significantly. While in grow-out ponds, water temperature, transparency, dissolved oxygen content, alkalinity and pH found to vary significantly with the size of the ponds and sampling periods. However, the mean values of chlorophyll-a did not vary significantly. The phytoplankton community in grow-out ponds consisting of 63 genera representing four groups of phytoplankton such as bacillariophyceae (16), chlorophyceae (32), cyanophyceae (13), euglenophyceae (2). While 21 genera belongs to four groups of zooplankton viz.; copepoda (5), rotifera (10), cladocera (6) and crustacean larvae were identified throughout the study period. A total of 61 genus of plankton were recognized from nursery ponds. In the present study, 49 phytoplankton genus were identified with 26 belongs to chlorophyceae, 12 to bacillariophyceae, 9 to cyanophyceae and 2 to euglenophyceae. Whereas, 12 genera of zooplankton consisting 6 genera of rotifera, 3 to copepoda, 2 to cladocera and 1 to crustacean larvae. However, the planktonic communities both in nursery and grow-out pond did not vary significantly throughout the study period. Total mean (±SD) abundances of phytoplankton were recorded as 16.69±4.71, 16.41±4.64, 16.20±4.27× ͳͲଷ cells/L in pond 1, 2 and 3 respectively in grow-out ponds. On the other hand, the mean (±SD) abundances of total zooplankton were recorded as 7.33±2.85, 7.12±2.69 and 6.79±2.64 cells/L for pond 1, pond 2 and pond 3 respectively. The mean values of total plankton were 23.55±×10³, 23.04×10³ and 22.51 ×10³ cells/L. While in nursery ponds, the mean (±SD) abundances of total phytoplankton were 18.48±1.81, 18.58±2.01 and 18.61±1.06 (× ͳͲଷ cells/L) recorded in sampling pond 1, 2, and 3 respectively. It can be concluded that the water quality parameters and planktonic abundance of grow-out and nursery ponds found within optimum and suitable ranges.