• DO is the most important and critical water quality parameter because of its direct effect on the feed consumption and metabolism of shrimp as well as indirect influence on the water quality.
• Maintenance of adequate level of dissolved oxygen in pond water is very important to shrimp growth and survival. 
• DO can be affected by many factors particularly water temperature, respiration of plants and animals and the level of organic matter.
• DO should be maintained in the range of 3-10 mg/l. For penaeid shrimp, optimum concentration of DO for maximum growth rate is 6 ppm.
• Prolonged exposure to low oxygen content causes low feed consumption which leads to slow growth, anoxia and the culture organisms become inactive and they are susceptible to disease. 
• DO in the waters come from two sources: 
  • As a by-product of photosynthesis and
  • Diffusion of atmospheric air.

Low level of oxygen concentration can be caused by a number of reasons 

• Dissolved oxygen decreases when temperature and salinity decrease.
• Oxygen concentration decreases depending on the depth of water.
• Dissolved oxygen normally decreases during night time. During the day, algae and plankton photosynthesize (with sunlight) and create oxygen dissolved in water. Absence of sunlight at night prohibits photosynthesis activities. At night, on days without sunlight or with overcast weather and rain, water will not have enough dissolved oxygen for shrimps.

Some symptoms of shrimp when water with dissolved oxygen is lacked:

Shrimp concentrates near water surface, edges of ponds, near position where water comes in; lethargic shrimp with strong respiratory rate, coma and possible death in shrimp.

Effects of DO in shrimps:

How to overcome the lack of DO in the pond?

• Increase the number of aerators. Normally dissolved oxygen is increased by using paddlewheel aerator or aeration blower. The use of aerators result in mixing of water at surface and bottom and breakdowns DO stratification and also can eliminate black mud formed at interface of pond water and bottom mud.
• Carryout water exchange to flush out the settled sediments/ pond waste and oxygen depleted water. Flow through water exchange can also be done.
• Over feeding should be avoided in order to maintain the DO level. One of the effects of overfeeding is to decrease the feed conversion efficiency.
• Application of DO enhancers can be undertaken to increase the DO level in the pond water as well as to oxidation of organic matter settled on the pond bottom due to the plankton crash. While Hydrogen peroxide, Pottasium permanganate provides an immediate burst of oxygen in the pond. Several commercial products containing compounds such as Calcium peroxide and Sodium perporate/ per carbonate are effective oxygen enhancers to overcome the sudden drop in DO of the pond.