The role of several conventional physical and chemical indicators in aquaculture
As the saying goes, raising fish first raises water, which shows the importance of water environment in aquaculture. In the breeding process, the quality of aquaculture water quality is judged mainly by detecting several indicators such as pH value, ammonia nitrogen, nitrite nitrogen, sulfide and dissolved oxygen. Therefore, it is very important to understand the role of several physical and chemical indicators in the water .
Acidity and alkalinity is a comprehensive indicator that reflects the water quality, and it is also a key factor that directly affects fish health. Practice has proved that the pH of the optimal water environment for fish growth is between 7 and 8.5. Too high or too low will affect the growth of fish and even cause fish death. Fish in alkaline water with pH higher than 9.0 will suffer from alkalosis, and will cause the fish to secrete a lot of mucus, which will affect breathing. The pH higher than 10.5 will directly cause fish death. In acidic waters with a pH lower than 5.0, the blood oxygen-carrying capacity of fish is reduced, causing hypoxia, dyspnea, reduced food intake, reduced food digestibility, and slow growth. Acidic water also leads to a large number of fish diseases caused by protozoa, such as sporozoites and ciliates.
2. Dissolved oxygen
Dissolved oxygen concentration is a key indicator of the quality of aquaculture water, and the dissolved oxygen in aquaculture water should be kept at 5-8 mg/L. Insufficient dissolved oxygen can cause floating heads, and in severe cases, it will affect the growth of fish and cause the death of pan-ponds.The concentration of dissolved oxygen in the water body directly affects the content of toxic substances in the water body. Maintaining sufficient dissolved oxygen in the water body can reduce the content of toxic substances such as nitrite nitrogen and sulfide. Sufficient dissolved oxygen in the water can enhance the immunity of breeding objects and enhance their tolerance to adverse environments.
1. Nitrite nitrogen
The content of nitrite nitrogen in the water exceeds 0.1mg/L, which will directly harm the fish. The hindered nitrification reaction of water is the direct cause of the production of nitrite nitrogen. The nitrification reaction of water nitrifying bacteria is affected by temperature, pH and dissolved oxygen in water. Therefore, the nitrite nitrogen content in water is closely related to water temperature, pH and dissolved oxygen.
The toxicity of sulfide mainly refers to the toxicity of hydrogen sulfide. Hydrogen sulfide is a highly toxic substance, low concentration affects the growth of aquaculture objects, and high concentration will directly lead to poisoning and death of aquaculture objects. The harm of hydrogen sulfide is similar to that of nitrite, mainly affecting the oxygen-carrying function of the blood of fish, resulting in hypoxia of fish. The concentration of hydrogen sulfide in aquaculture water should be controlled below 0.1mg/L.
Therefore, accurately grasping these testing items, carrying out regular testing, and adopting corresponding measures in a timely manner can greatly improve the survival rate of fish and shrimp and reduce the cost of breeding.
Post time: Jan-12-2022