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Good Aquaculture Practices

Ammonia & Nitrite Management

Ammonia is the major toxic component produced continuously by shrimps during culture. It can also accumulate in the water due to the decomposition of organic matter as excess feed, faeces, dead shrimp and dead algae. Of all the water quality parameters which affect shrimp, ammonia is the most important after oxygen. In water, Ammonia present in two forms, Ionized (NH4+) and un-ionized (NH3) which together are called the Total Ammonia Nitrogen (TAN). In these two, un-ionized (NH3) ammonia is very dangerous.

The Overall Shrimp survival, health and growth is hampered by high level of ammonia and nitrite. Regular conversion of Ammonia to Nitrite and then to harmless Nitrate is done by the Nitrifying bacteria present in the pond. But when this rate of conversion is slower than the ammonia production, it leads to buildup of Ammonia and nitrite in ponds.

Ammonia and Nitrite build-up in ponds can be controlled by adopting combined strategies as,

Better Feed management.
Proper Algal bloom maintenance.
Regular Pond bottom maintenance.
Favourable Water quality parameters.

Relative toxicity of Ammonia, Nitrite and Nitrate

Condition	Ammonia(ppm)	Nitrite(ppm)	Nitrate(ppm)
Happy	0.0	0.0	0.0
Sad	0.5	2.0	25
Sick	1.0	3.0	50
Dead	>1.0	>3.0	Varies by species

GROWTH PROMOTORS

There is a great concern of increasing Antibiotic resistance of pathogens, in the human food chain. To comply with the International Regulatory Challenge of Non Antibiotic Usage and focus on Best Aquaculture Practices (BAP) and Aquaculture Stewardship Council (ASC), utmost precaution has to be taken in choosing the farm inputs.
Feed supplements are nutritional substances of various compositions as Gut Probiotics, Vitamin and Minerals, Organic acids, Immuno-stimulants, Ammonia binders etc...
As the stages of culture grows, there is depletion of natural nutrition present in the environment, as it is consumed by the shrimps but there is no addition of fresh water for Biosecurity reasons.
Many demanding conditions arises which necessitates the use of feed supplements from external sources to help or improve a particular function in shrimp system.

Conditions and purpose of different feed supplement

Stage of Culture	Conditions / Purpose	Action / Effect	Supplements to be added
Seed Stocking	To Propagate and increase probiotics population in the gut	Increases Survival	Stocking Probiotics
Upto 30 DOC	To increase immunity	Increase Disease resistance	Immuno-stimulants
After 30 DOC	To improve feed intake	Improves digestibility by producing feed digesting enzymes	Feed Probiotics
	To improve nutrient absorption	Increase absorption capacity of Gut	Organic acids
	To improve shell quality and body weight	Provides sufficient Macro and Micro minerals for Proper shell development	Minerals, Vitamins and Aminoacids.