1. Ringworms
The gills of the diseased fish have increased mucus, all or part of them are pale, breathing is difficult, the gills are significantly puffy, the naked eye is not easy to see the insect body, and the live insects can be seen by taking fresh gill filaments under the microscope, and hooking on the gill filaments to do ant-like movements. The central large hook and marginal hook of the chitin of the ringworm pierce into the gill tissue, causing lesions, affecting the respiratory function of the gills, causing death in the fish. This is a common multi-morbidity and is found throughout the country. It is mainly prevalent in late spring and early summer, and is mostly harmful to silver carp and grass carp species. The bad gill ringworm is less than 1 mm long and is difficult to observe with the naked eye on the gills of the fish. The obvious difference between ringworms and third-generation insects is the presence or absence of eye spots; the obvious difference between bad gill ringworms and medium-sized ringworms is the curved shape of the end of the anchor hook, one wavy bending, and one curved with a larger curvature.
2. Double-hole trematodes
Also known as cataract disease, blindness, eye loss or compound chicosomiasis. The pathogens are Hubei double-hole fluke and Ni's double-hole fluke, whose tail larvae and cysticer parasitize in the body of the eye crystal, thereby causing blindness and affecting feeding and growth. Double-hole trematodes are internal parasites, and the middle host is snails, so the pond should be cleared thoroughly. Completely killing pathogens when clearing ponds can play a good therapeutic effect.
3. Wheel worms
Rotiferosis is a very common protozoal disease in fish, which parasitizes and secretes a large amount of mucus in severe cases, and a layer of white wings appears on the body of the fry in the denser parts of the wheelworm, such as fins, heads, and body surfaces. When endangering the fry in the pond for about ten days, it was found that the swarms swam wildly along the edge of the pond, the mouth was full of mucus, the mouth was difficult to close, it was not feeding, and the phenomenon of "running horses" was present, and the fish body was emaciated.
4. Small melon worms
The small melon worm belongs to the protozoa phylum, ciliate, notch family, small melon worm genus, mainly parasitizing the skin, fins, gills, head, mouth and eyes of fish, forming a small white dot-like sac, which is visible to the naked eye, so it is called "white spot disease". In severe cases, the fish body is covered with a white film. Microscopic adults have large horseshoe-shaped nuclei, while juveniles have only round, oval, or rod-shaped nuclei. Sick fish swim slowly, float on the surface of the water, and sometimes swarm around the pool, and the fish body constantly rubs against other objects, or jumps out of the water, and soon dies in batches. Small melon insects in the process of killing is very easy to produce sacs, once the conditions adapt to the growth of small melon insects, the eggs in the sacs reproduce again, in the process of killing so repeatedly, so it is difficult to completely kill. Small melon worms are not tolerant of high temperature, when the water temperature reaches 28 ° C automatically die, small melon worms parasitize in the gills of fish easy to cause fish physiological breathing difficulties leading to death, so once found that fish infected with small melon worms, pay attention to oxygenation, internal medication to enhance resistance. Ponds infected with small melon worms are easy to recur in the future, so be sure to clean the pond and disinfect them to prevent infection with small melon worms in the coming year.
5. Myxosporidium
The pathogen is myxosporidium, which has many species, the insect body is relatively small, the parasitism is very extensive, almost every fish can be infected with various organs, and even several kinds of myxosporidium parasitize in the same organ of the same fish.
Common fish disease symptoms and hazards caused by myxosporidium:
Skin diseases caused by myxosporidium: the pathogen is crucian iodosporus. Parasitizing the subcutaneous muscles, the posterior upper end of the head of the diseased fish forms a nodular cyst, gradually expanding so that the muscles decay, the fish body darkens, emaciates, and finally dies.
Gill disease caused by myxosporidium: the pathogen is coccidioides, heteromorphic iodospores, etc. Silver carp, bighead carp, carp, crucian carp, etc. can be infected from fry to adult fish. There are many grayish-white dotted or noomatous sacs on the gills of diseased fish, which are difficult to breathe and hinder growth and development, causing a large number of deaths.
Intestinal diseases caused by myxosporidium: the main pathogens are grass fish cake-shaped iodine bubble worm, silver carp myxo worm, symmetrical iodine bubble worm and so on. Its vegetative bodies form sacs in the tissue of the intestinal mucosa, and some species not only invade the mucous membrane and form sacs, but also pass through the intestinal wall and form sacs outside the intestine. It clogs the intestines and destroys tissue cells, hinders feeding, digestion and absorption and is emaciated to death.
Silver carp and bighead carp madness caused by myxosporidium: the pathogen is silver iodine bulbophyllum, which invades the nervous system and sensory organs of fish. The sick fish is extremely emaciated, the body color is gray and dull, and the white putted cysts can be seen in the brain cavity. The tail is upturned, swimming wildly, convulsing and whirling, losing its balance, sometimes sinking to the bottom of the water, sometimes lying on the surface of the water, and soon dying.
Myxosporidium also often invades the liver, kidneys, spleen, heart, reproductive glands, bladder, fat, muscle and fat of diseased fish, causing different degrees of lesions.