Algae produce most of the oxygen in the pond and remove most of the carbon dioxide and many of the nutrients. Algae also consume oxygen, produce carbon dioxide, cause pH to fluctuate, and release nutrients into the water as they die. Algae populations change continuously, because different species nourish at distinct temperatures and under various pH and nutrient conditions. The only way a fish farmer can become an efficient producer is to continuously monitor and keep records of bloom conditions, oxygen concentration, and other water quality factors. Dissolved Oxygen Low dissolved oxygen is by far the most common water-quality problem in catfish production ponds.
Oxygen diffuses into water from the air.
Diffusion is a slow process unless it is aided by the action of wind or some type of mechanical agitation that mixes air and water together. Most pond oxygen comes from photosynthesis. Photosynthesis is the process by which plants make food from carbon dioxide, water, nutrients, and sunlight. The by-product of photosynthesis is oxygen, which dissolves into the water. At night, no oxygen is produced and the respiration of the algae and fish and the decomposition of wastes by bacteria remove oxygen from the pond.