Optimizing Water Quality for Black Tiger Shrimp or P.Monodon 

Effective water quality management is paramount in the successful aquaculture of Penaeus monodon, commonly known as Black Tiger shrimp. This species exhibits specific requirements and sensitivities to various environmental factors, ranging from temperature and salinity to dissolved oxygen and pH levels. Understanding and maintaining these parameters within optimal ranges are essential for promoting growth, minimizing stress, and preventing health issues in the shrimp population.

Temperature

  • Black Tiger shrimp thrive best in temperatures ranging from 28°C to 30°C.
  • However, if temperatures exceed 33°C in poor water quality or 35°C in good quality water, shrimp become stressed and may stay at the pond bottom.
  • Stress can lead to infections, disoriented swimming, or exhaustion if the environment doesn't improve.
  • Below 28°C, shrimp metabolism and growth slow down, with feed intake decreasing below 20°C.
  • Shrimp cannot survive temperatures below 13°C.

Salinity

  • The ideal salinity range for Black Tiger shrimp is between 10 and 25 ppt.
  • Bagda shrimp thrive best at 30 ppt salinity for optimal growth.
  • Both shrimp species can tolerate salinities ranging from 5 to 38 ppt due to their euryhaline nature.
  • The early life stages of shrimp and prawns require standard seawater salinities, but they can adapt to brackish or freshwater as they grow.
  • Maintaining the optimum salinity range in aquaculture ponds ensures better survival and growth of the shrimp.
Dissolved Oxygen
  • Maintaining dissolved oxygen levels above 3.5 ppm is crucial.
  • Oxygen in the air, constituting over 21%, serves as a significant reservoir.
  • Oxygen concentration in water is limited by its solubility.
  • Supplemental aeration is typically provided at night when DO levels drop below 4.0 ppm.
  • Paddlewheel aerators can increase dissolved oxygen from 0.05 to 4.9 mg/l within 4 hours in a 0.5 ha pond.
  • Combining aeration and water exchange rapidly improves low dissolved oxygen levels in aquaculture ponds.

pH

  • pH 7 is a condition of neutrality and routine aquaculture occurs in the range of 7.0 to 9.0(optimum is 7.5 to 8.5).
  • Exceedingly alkaline water (greater than pH 9) is as dangerous as ammonia toxicity increases  rapidly
  • At higher temperatures, fish are more sensitive to pH changes. A certain range of pH (pH 6.8 – 8.7) should be maintained for acceptable growth and production.
    Ammonia 
    • High ammonia levels can result from overfeeding and the decay of excess protein-rich feed.
    • Ammonia gas, when combined with ammonia excreted by fish, may accumulate to dangerous levels.
    • Nitrifying bacteria partially mitigate ammonia levels by converting it to non-toxic nitrate (NO3 -).
    • Ammonia is transformed from toxic ammonia (NH3) to non-toxic ammonium ion (NH4 +) in environments with a pH below 8.0.
    • AquaCare Control provides water conditioning microbes that improve water quality by actively utilising ammonia compounds including nitrite and nitrate.
    Hardness
    • Water contains various dissolved inorganic substances, including calcium and magnesium metals, along with carbonate ions (CO3 -2), which determine its hardness.
    • The recommended hardness range for aquaculture is 40 to 400 ppm.
    • Hard water can buffer the harmful effects of heavy metals like copper and zinc, which are typically toxic to fish.
    Turbidity
    • Water turbidity refers to suspended material obstructing light penetration.
    • High turbidity limits bottom-layer photosynthesis and can lead to temperature and DO stratification.
    • Excessive suspended clay particles can clog gills and harm prawn tissues.
    • Colloidal particles, sourced from erosion or water, contribute to unwanted turbidity.
    • Alum and ferric sulfate are more effective than hydrated lime and gypsum in removing clay turbidity.
    • Treatment rates vary based on soil composition.

    In conclusion, the sustainable cultivation of Penaeus monodon relies heavily on meticulous water quality management. By carefully monitoring and regulating factors such as temperature, salinity, dissolved oxygen, pH, ammonia levels, hardness, and turbidity, aquaculturists can create an environment conducive to the health and growth of Black Tiger shrimp. Through proactive measures and the application of appropriate techniques, aquaculture operations can ensure the viability and productivity of P. monodon while minimizing environmental impact.