The experiment was carried out from July 2010 to June 2011 in six ponds namely as Nilkamal, Lalkamal, Salsabil, Tarangotanu, Jolpoddo and Nilpoddo situated at PSTU. The area of Nilkamal, Lalkamal, Salsabil, Tarangotanu, Jolpoddo and Nilpoddo were 64, 99, 162, 50, 62 and 68 decimal respectively and depth were 7, 7, 8, 7, 7 and 7 feet respectively. A number of water quality parameters such as water temperature (°C), dissolved oxygen (mgl-1), pH, ammonia (mgl-1), total hardness (mgl-1) and total alkalinity (mgl-1) were measured weekly. Temperature, pH and dissolved oxygen were measured on the spot and rests of the above parameters were measured at Fisheries Laboratory, Faculty of Fisheries, PSTU. Water samples were collected between 8.00 to 9:00 am from each pond surface to a depth of 20 cm.
Water temperature (°C)
During the study period, water temperature was recorded with the help of a thermometer.
Dissolved oxygen (mgl-1)
The dissolved oxygen of water was measured by using a portable digital DO meter (YSI, model 58) on the spot.
pH
pH of pond water was determined by a direct reading digital pH meter (Jenway, model, 3020).
Ammonia (mgl-1), Total Alkalinity (mgl-1) and Total Hardness (mgl-1)
During the study period, water samples were collected in a plastic beaker and brought to the laboratory. Ammonia, total alkalinity and total hardness were determined with the help of respective HANNA test kit.
Statistical analysis
For the statistical analysis of data, one-way analysis of variance (ANOVA) and Tukeys Test was performed using the SPSS (Statistical Package for Social Science, version-12.0). Significance was assigned at the 5% level.