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Dissolved oxygen in water in shrimp pond

Dissolved oxygen (DO) is an important factor in aquaculture production. Low dissolved oxygen in water can make shrimp and fish die

Dissolved oxygen (ppm)

Effects on shrimp

0.3

Shrimp die

1.0

Anoxia in shrimp, shrimp may die

2.0

Shrimp cannot grow up

3.0

Shrimp grow slowly

4.0

Shrimp grow normally

5.0 - 7.0

Shrimp grow healthily and rapidly

The best levels of dissolved oxygen in shrimp ponds are equal to or higher than 5 ppm.

Oxygen concentration decreases when water depth increases. Dissolved oxygen also decreases when temperature and salinity of water decrease.

During the day, with sunlight, algae and plankton photosynthesize to create oxygen dissolved in water.

At nighttime, on days without sunlight or with overcast and rainy weather, water in ponds will not have enough dissolved oxygen for shrimp. In this case, dissolved oxygen should be increased by using paddlewheel aerators, aeration blowers, or changing a part of the ponds’ water.

Excessive use of chemicals to remove algae, or insecticides to eliminate aquatic plants can also cause a shortage of dissolved oxygen.

Some symptoms of shrimp living with low dissolved oxygen in water are: Shrimp concentrates near the water surface, edges of ponds, or near positions where water is pumped into ponds; lethargic shrimp with a strong respiratory rate, coma, and possible deaths in shrimp.

When too much air is saturated in water, dissolved air will invade shrimp’s circulatory system and form bubbles that obstruct shrimp’s blood flow. This creates the "gas bubble disease" that can cause deaths in shrimp.

Water in ponds is saturated with air when:

• Photosynthesis of phytoplankton is too much (The transparency of water can be measured by using the Secchi disk, if the reading is at 10cm or less).

• The water temperature increases.

• Strong disturbance between water layers occurs (at the positions where aerations and water pumps located)

 

 

To overcome the lack of oxygen in shrimp ponds:

- Ponds need aeration. If you use water hyacinth, duckweed, or water spinach to create shelters for shrimp and fish when it's sunny, gather them together in a corner of a pond and do not have the plants cover more than 1/3 of the pond surface.

- Do not excessively feed and fertilize shrimp or feed. This method will reduce the concentration of dissolved oxygen because dead algae consume oxygen and generate toxic CO2, NH3, or H2S.

- Change pond water with good-quality water.

- When a large number of shrimp and fish swim on the water surface, or become weak and active (they swim lethargically, swim near edges of ponds, have no reaction to sound), you need to provide them aeration. Use aerators and supply new water.

- Use hydrogen peroxide H2O2: 2H2O2 → 2H2O + O2

When the levels of dissolved oxygen are less than 4 ppm, shrimp swim near the water surface, they need more aeration and water changes. Check and adjust their feed intake; avoid feeding shrimp fresh food; add vitamins, minerals and supplements to shrimp feed; manage the quality of water carefully.

If the amount of dissolved oxygen is too low in the morning and too high in the afternoon, it will make algae thrive. To solve this issue, control shrimp feed, use 10 – 20 kilograms of Super-Calcium (CaCO3) in each 1600 m2, turn on aeration at night, and manage the quality of water.

When the amount of dissolved oxygen is too low, use more air blowers.

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