Aquaculture Fish Farming Enviroment Requirements

Yangfan Mesh Factory Manufacture Deep Sea aquaculture fish farming cage Since 1997,over 25 years experienced in fishing gears production.Please allow us to introduce the living environment of fish in cages in deep sea, including abiotic (such as dissolved oxygen, temperature, pH value, etc.) and biological (such as zooplankton, phytoplankton, etc.) environment. The quality of water quality is closely related to the growth and survival of fish. Only by mastering the relationship between fish and water and the characteristics of water quality changes can we artificially control and improve water quality and increase fish production. 

1. Water quality and environment

Main water quality factors 

1. Dissolved oxygen content Dissolved oxygen in 

water is one of the necessary conditions for the survival of fish in cages. According to observation and determination, when the dissolved oxygen in the water reaches more than 2 mg/L, the fish grows normally, the digestion and absorption of the feed is better, and the feed coefficient is also low; when the dissolved oxygen is below 1.6 mg/L, the fish grows normally. When the food intake decreases, the feed coefficient is about twice as high as when it is above 2 mg/L; when it drops to 1.1 mg/L, the oxygen content in the water is insufficient, the respiration rate of the fish is accelerated, and the phenomenon of "floating head" occurs; when it drops to 0.2- When it is below 0.8 mg/L, it begins to suffocate to death. 

Increasing the amount of dissolved oxygen in the water, especially the amount of dissolved oxygen in the bottom of the water, can promote the decomposition of organic matter in the sludge and accelerate the material circulation of the pond; reduce the accumulation of harmful intermediates such as organic acids, ammonia, and hydrogen sulfide, and promote the growth of feed organisms. Growth and reproduction play an important role. 

The distribution and change of dissolved oxygen in ponds are very complex, mainly restricted by oxygen-enhancing and oxygen-consuming factors, especially high-yield fish ponds, which are very nutrient-rich, plankton and stocking fish are relatively dense, and both oxygen-enhancing and oxygen-consuming are very large. Therefore, the amount of dissolved oxygen is very unstable and varies diurnal, vertical and horizontal. 

( 1) Diurnal variation 

Phytoplankton photosynthesis is the main source of oxygen in the pond, generally accounting for 56%-80% of the oxygen source. The rest comes from wind blowing waves, so that the oxygen in the air dissolves directly into the water. 

Oxygen consumption, including the respiration of fish, plankton, benthic organisms, and bacteria; fermentation and decomposition of suspended or dissolved organic matter, feces, residual bait and bottom sludge. 

The diurnal variation of dissolved oxygen is highest at noon and lowest in early morning, "Senior...".

Under normal circumstances, "water respiration" (including the respiration of zooplankton, plants, bacteria, feces dissolved in water, and the fermentative decomposition of base bait organic matter) accounts for about 60-65% of oxygen consumption; the substrate (including benthic organisms, Humus, etc.) oxygen consumption accounts for about 15-20%, and fish respiration accounts for about 20-25%. 

( 2) Vertical change 

The vertical change of dissolved oxygen in the pond is affected by the transparency of the water and the distribution of phytoplankton. Since the light intensity of the upper water layer is stronger than that of the bottom layer, there are more phytoplankton than the bottom layer, resulting in differences in photosynthesis and oxygen production in each water layer. The dissolved oxygen in the surface layer is high, and the dissolved oxygen in the bottom water is low. In order to improve the dissolved oxygen conditions of the bottom water, it will play a good role in promoting the uniform distribution of dissolved oxygen in various water layers by starting the aeration and stirring the pool water at noon. 

(3) Level change 

Because the water is affected by the wind, the amount of phytoplankton in the downwind is larger than that in the upwind, so the photosynthetic oxygen production is more than that in the upwind. Therefore, the fish floating heads generally tend to be upwind. 

⑷ Seasonal changes 

Due to the seasonal changes in climate and phytoplankton, the dissolved oxygen in the water is the highest and lowest in a year, both in summer and autumn. In summer and autumn, the water temperature is high, and there are more phytoplankton than in winter and spring, so the photosynthetic oxygen production is also high. However, the respiration and fermentative oxygen consumption of each oxygen-consuming factor were relatively enhanced. Make the dissolved oxygen in the pond water to the lowest point in the morning. Therefore, the difference of dissolved oxygen between day and night in summer and autumn is large, but the difference is not obvious in winter and spring.

For more deep-sea aquaculture cage knowledge, please call our professional sales team of Yangfan Nets for consultation and discussion, and welcome all fishing elites to visit our factory for guidance, thank you!