How Do Fish Spend the Winter? A Detailed Guide to Fish Overwintering Methods
When the cold winter arrives, animals that can hibernate all go into warm burrows to hibernate, while animals that cannot hibernate migrate south to warm places to spend the winter. Especially when winter comes in the north, it is almost a state of “a thousand mountains with no birds flying, ten thousand paths with no footprints of people.” So how do fish, as animals, spend the winter?
I. How Fish Spend the Winter
If they are fish living in the wild, most do not hibernate; they sink to warm places at the bottom of the water to live and reduce their activity. For fish artificially farmed in ponds, however, relevant technical measures must be taken to pass safely through the low-temperature season. The main methods include still-water overwintering, flowing-water overwintering, cage overwintering and indoor overwintering.
For ornamental fish raised indoors, overwintering is generally carried out by measures such as changing feeding times and adjusting water temperature.
In the warmer regions of the south, fish living in the wild do not need to carry out related overwintering activities, while in the colder regions of the north, because the phenomenon of water contracting when hot and expanding when cold causes the lower water layer to have a higher temperature, fish gather there and only float up to the surface to move about when the weather is clear.
When artificially farmed fish are overwintering, it should be ensured that the non-freezing water layer of the overwintering pond is above 1-1.5 m, and the pond bottom is required to be flat, with a silt thickness of about 10 cm, because the silt contains a large amount of humus, which, although it can supply fertilizer, retain fertilizer and regulate water quality, in addition, the fish must also be disinfected before overwintering to avoid causing disease. Among these, still-water overwintering means placing farmed fish in suitable still small water bodies such as ponds to overwinter, generally used in areas lacking flowing-water conditions. Flowing-water overwintering is the use of water of suitable temperature and rich in dissolved oxygen that continuously flows in and out on its own to renew the fish overwintering water body, so that the fish can overwinter safely. Cage overwintering involves choosing a reservoir or lake with sufficient dissolved oxygen and suitable water temperature to place cages, so that the fish overwinter in cages sunk underwater. Indoor overwintering involves building plastic film greenhouses or glass greenhouses over the fish pond to keep warm and use sunlight to raise the temperature, so that the fish can overwinter safely.
When tropical ornamental fish raised indoors are overwintering, first the feeding time should be changed, generally feeding at around ten in the morning, when the difference between water temperature and air temperature is relatively small and the impact on the ornamental fish is also relatively small; second, attention should be paid to changes in water temperature, and when the water temperature is too low, a heating rod should be used in time to heat it, creating a good living environment for the ornamental fish.
II. Basic Information About Fish
In the animal kingdom, fish are divided into the class Chondrichthyes and the class Osteichthyes, and are one of the most widely distributed species in waters worldwide. There are currently 24,618 living species of fish worldwide, and new species are continuously increasing at an average rate of 150 species per year. Fish are mainly divided into tropical fish, temperate fish and cold-zone fish, etc., and there are many kinds under each.
Fish and humans have an indissoluble bond. As early as the early period of primitive humans, fish were one of the main sources of protein. The book Erya from the early Han Dynasty in China had already divided animals into 4 categories: insects, fish, birds and beasts, which shows how long humans have known about fish. Eating fish regularly can play a role in strengthening the brain, protecting the heart and lowering blood lipids, and efficiently supplementing calcium.
The above is some basic knowledge about fish. When overwintering fish, it is still necessary to analyze according to the specific situation, and different fish also have different requirements for their living environment.