Sludge: An Obstacle in Shrimp Farming and Strategies to overcome the adverse effects of sludge

Hello everyone,

          Myself SRIHARI N C, B.F.Sc., Here we are about to discuss How a Sludge is an obstacles for shrimp farming and Strategies to overcome it’s adverse effects

(I) What is Sludge:

• Sludge is a semi-solid slurry substance that is produced in pond environment due to various aquaculture practices.

• Sludge is majorly composed of uneaten feed, animal fecal, dead organisms and planktons and it is rich in nutrients (Nitrogen and Sulphur)

(II) How a sludge is an obstacle to shrimp farming:

• Microorganisms are divided into 3 groups based on requirement of oxygen

i)Aerobic – Needs oxygen to survive

                                                                   ii)Anaerobic – No need of oxygen to survive

                                                                 iii)Facultative aerobic – Can survive with/without of oxygen

• Here the anaerobic microorganisms breaks the oxidised organic nutrients without utilization of oxygen and the process is called Reduction

• For example, the anaerobic microorganisms reduces Nitrate to Nitrite and Ammonia and Sulfate to Hydrogen Sulphide which are highly toxic to aquatic organisms

• The combination of anaerobic environment and high nutrient level provides an ideal environment for proliferation of microorganisms that can harmful to shrimp either directly as a pathogen or indirectly as a toxic compounds

• These pathogens and toxic compounds create a stressful environment for shrimp and results in high mortality rate, low survival rate, shunting of growth or slow growth, outbreak of disease, etc.

(III) Strategies to overcome the adverse effects of sludge

• Maintaining high Dissolved Oxygen (DO) in water column will support the non-pathogenic microbial community to survive 

• Proper feed management to prevent overfeeding

• Scrapping and removing of sludge from pond bottom between the culture

• Disinfecting the pond bottom to eliminate the potential pathogen in subsequent culture practice

• Placing the Aerators in such a way that it drifts the uneaten feed, animal fecal, dead and decaying organisms and concentrate them in a small area of the pond (probably center of the pond)

• Using of probiotics (bioremediation) that maintain the water bloom, supports the non-pathogenic microbs and breakdown the accumulated sludge aerobically

• Having the central drainage system to remove the accumulated sludge periodically

• Having Shrimp Toilet, that covers 1% to 2% pond are, from where the accumulated sludge can be removed easily using siphoning motor without disturbing the accumulated sludge

•Regular water sampling to monitor the level of toxic nutrients in water column

• Proper pond bottom soil sampling before each culture

Soil parameters	Optimum level
pH	6.0 – 7.5
Total organic Carbon	2%
Total organic Nitrogen	5 – 75 mg/100g soil
Soluble Sulphur	< 0.4%
Total phosphate	5 mg/100g soil
Redox Potential	>- 100mV

(IV) Conclusion:

• As I have said before, Sludge is an obstacles in shrimp farming and it have adverse effect on production management. Many farmers follow many strategies to overcome the effects of sludge and here I have explained some of those strategies in brief. So, by following BMP and BAP in shrimp farming and sludge management we can overcome the adverse effects of sludge.

For further contact,

Mr. SRIHARI N C, B.F.Sc.,

+918270776354 (WhatsApp / Call)