Water temperature enhancement in polyhouse tanks in a sub-tropical region during winter season

An experiment was conducted at ICAR-Central Institute of Freshwater Aquaculture, Bhubaneswar during winter season (December to February) of 2011-2012 to observe the variations in temperature and some physico-chemical parameters of water in control and experimental tanks (each with 10 m2 area and 1.0 m depth). Control tank was without LDPE cover and the experimental tanks were covered with LDPE film of 200µ at different heights (T-1: 0.3 m, T-2: 0.6 m, T-3: 0.9 m) from tank water level. The physicochemical parameters, such as dissolved oxygen; carbon dioxide; pH of water; and temperature of both air and water were recorded in different durations for different experiments. From the study it was observed that, water temperature rose up to 5.4, 3.6 and 3.2C in T-1, T-2 & T-3 tanks, respectively than the control one. The other water parameters were found within the acceptable range of fish culture.