How does toxic gas affects fish and shrimp in aquaculture?

Posted by Kumaran J on

Don’t let you fish and shrimps live with this toxic gas!!!

Where the toxic gas comes from?

Generally Hydrogen sulphide (H2S) is a toxic gas for aquatic animals. Under anaerobic conditions, some bacteria utilize the uneaten feed and organic matter in the pond bottom and release rotten egg smell H2S gas.

What factors cause H2S in the aquaculture pond?

  • Plankton bloom or crash, 
  • High pond depth, 
  • Leftover feed, 
  • Sandy or loose soil, 
  • Leakage in pond bottom sheets can lead to H2S gas production.

How does it spoil your culture?

H2S gas affects the oxygen receiving capacity of animals and makes them more vulnerable to diseases. The other potential effects are:

  • High ammonia & nitrite levels
  • Plankton bloom, Low pH
  • Low feed consumption
  • WFD, black gill disease, and loose shell syndrome.

 It is also called ‘Silent killer’, which is more dangerous than ammonia and nitrite.  

How to check H2S of the pond?

You may sense H2S by extreme odor like rotten egg smell from pond water. However, measuring the H2S gas is more complex, usually Lab analysis like methylene blue method will reveal their presence. Please note that safe level of H2S is much lower than of ammonia and nitrite.

Preventive measures:

  1. Avoid farming in acid sulphate soil
  2. DO, temperature, PH should be in the optimal range to avoid H2S gas production. 
  3. Control feeding.
  4. Monitor PH regularly and apply lime to increase PH.
  5. Maintain proper aeration 
  6. Periodic sludge removal
  7. Use probiotics and sulphur utilizing bacteria. 
  8. Optimum pond depth to avoid thermal fluctuations.
  9. Control algal bloom.
  10. Use zeolite to absorb H2S.

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