First, the water temperature is too high
Too high water temperature will affect the growth of fish, each fish has a suitable water temperature range for growth, therefore, in the summer, if the water temperature exceeds the appropriate temperature for fish growth, cooling measures should be taken.
Second, the transparency of water is too large and too small
Generally, nutrient-rich water and fish pond fertilizer water have a transparency of 30-40 cm. If the transparency is less than 20 cm, there are few plankton. None are suitable for fish growth.
Third, the dissolved oxygen in the water is too low
The most suitable dissolved oxygen for fish growth is 5-8 mg/L. When the dissolved water is less than 2 mg/L, oxygenation measures should be taken.
Fourth, bad water
The water color is light red or brownish red, foam or oil film appears on the water surface, and when the water has a peculiar odor and odor, it is extremely harmful to the growth of fish. In this case, the evil water should be released and the new water should be filled.
Fifth, the pH value in the water is too high
The pH value in the water should be 6.5-8.5, when the pH value in the water is lower than 5.5, freshwater ornamental fish, or higher than 10, can not be used as fishing water.
Sixth, the content of nutrient salts in water is too high
The amount of nutrient salts in water is closely related to the growth of fish. If nitrates in water are most easily used by green phytoplankton, the general content should be maintained at 1-2 mg/l. If it exceeds 3 mg/L, it is easy to cause hypoxia in the water and cause fish to die.
Seven, the content of dissolved gas in water is too high
Carbon dioxide in water is an essential substance for plankton, but the content should not be too high, generally should be less than 80 mg / l, if too high to fish is extremely harmful.
8. Harmful substances in water
Harmful substances in the water are cyanide, phenol, mercury, chromium, lead and petroleum, which not only poison fish, but also poison people who eat poisoned fish. Therefore, these sewage should be strictly entered into the fish pond.