*2.5.4. Temperature and dissolved oxygen*

The fluctuations in the temperature and dissolved oxygen do not have much influence on the yield of rice, but it matters for the production of aquatic protein. In summer, the water temperature for ASp is regulated by rice plant shading during summer [26, 74]. Anyhow the low/moderate temperatures are best suited for good yield of ASp. To maintain adequate temperatures for the better growth of fish, prawn, carb, crayfish, snails and other ASp, high amount of water needs to be maintained continuously in the ponds/trenches/refuges. The only way to maintain temperature in the rice-ASp system is by controlled water system.

The dissolved oxygen is an important factor that affects the survival and growth of ASp, and in extreme conditions, it may lead to death. Unsystematic management of ponds/trenches leads to pollution [75], resulting in reduced dissolved oxygen. Basically the reduced dissolved oxygen changes the physiochemical properties of water, thereby pond/trench ultimately shows effect on growing fish. Most of the times, dissolved oxygen is reduced due to overloading of nutrients in the ponds/trenches and also causes increase in cyanobacterial bloom, which depletes dissolved oxygen and shows poisonous effects on ASp [76]. The increase in photosynthesis in rice due to increased aeration is recorded with the fish movement in the rice field [77, 78].
