Technical Requirements

In aquaculture, it is necessary to focus on monitoring key water quality parameters such as pH value, dissolved oxygen, ammonia nitrogen and nitrite, which directly affect the health and growth of cultured organisms. The suitable pH value ranges from 6.5 to 8.5 for freshwater aquaculture and 7.0 to 8.5 for mariculture. A pH value below 4.4 or above 10.4 can cause large-scale death of fish and shrimp. Daily deviation from the suitable range will inhibit feeding and immunity, and long-term deviation will easily increase the mortality rate. Dissolved oxygen shall be ≥5 mg/L for more than 16 hours within 24 hours, and ≥3 mg/L for the remaining time (≥4 mg/L for salmonids during the ice-sealed period). A dissolved oxygen level higher than 12 mg/L is prone to cause bubble disease, while a level lower than 3 mg/L will lead to fish floating on the water surface or pond fish kills. Ammonia nitrogen shall be controlled below 0.2 mg/L, among which molecular ammonia (the main cause of toxicity) shall be ≤0.02 mg/L. The toxicity is significantly affected by pH and water temperature; even a slightly higher concentration can damage the gills of fish and shrimp and hinder their growth. The ideal value of nitrite is ≤0.1 mg/L, and it should be strictly controlled between 0.01 and 0.05 mg/L during the seedling stage and for sensitive species. Nitrite can induce methemoglobinemia, weaken oxygen transport capacity, and cause poisoning symptoms in severe cases. The suitable total hardness is about 50 mg/L for most freshwater fish, and ≥250 mg/L for crustaceans. Calcium and magnesium ions affect the molting of crustaceans and the growth of algae, helping to stabilize the water body. The suitable temperature varies with species: 20-32℃ for eurythermal fish and 22-32℃ for tropical species such as Litopenaeus vannamei. Abnormal temperature will disrupt metabolism and indirectly affect dissolved oxygen. Sulfide shall be ≤0.2 mg/L; a concentration of 0.1 mg/L will affect juvenile fish, and 0.3 mg/L can cause the death of all carp. Residual chlorine from disinfection shall be ≤0.02 mg/L; excessive residual chlorine will corrode gill tissue, and a concentration ≥0.1 mg/L is fatal to fish, shrimp and crabs. The appropriate turbidity is a transparency of about 30 cm; excessively high turbidity blocks light and clogs gills, easily inducing diseases. Accurate monitoring of these parameters can reduce the mortality rate by 30%-40%, which is the core of aquaculture risk prevention and control.

Integration of Aquaculture Parameters and Standard Limits

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The above content is compiled based on relevant standards. Deviations may exist during the compilation process. For any omissions or errors, please contact VVNA customer service for consultation or put forward your valuable opinions.