What are the fish diseases with similar symptoms observed by the naked eye during aquaculture, and how to identify them?

【Common problems】 In the current aquaculture, some common fish diseases with widespread epidemics and greater harm often have many similar symptoms, which bring certain difficulties to the diagnosis of fish diseases.

【Cause analysis】 Some different pathogens show similar symptoms of fish disease, but their pathology is different, such as not carefully distinguished, only one prevention and control measures are taken, which is easy to cause misdiagnosis.

【Solution】In the absence of diagnostic instruments and equipment, only by strictly distinguishing similar fish diseases can symptomatic treatment be achieved.

I. Differentiation of viral enteritis from bacterial intestinal and intracultural amoeba disease

The intestines of the sick fish of all three diseases are red.

Among them, the virus also causes congestion of the mouth, muscles, gills, fins, etc., and the intestinal mucosa generally does not decay and fall off; Bacterial enteritis does not have oral muscle congestion, the intestinal mucosa often ulcerates and suppurates, and there is a lot of milky yellow ascites;

Symptoms of intrapilottosis are similar to those of bacterial enteritis, but generally only in the posterior intestine.

Second, the identification of gill lid open fish disease

Gill-lid open-shaped fish diseases include rotiferiasis and ringworm disease. The former has typical symptoms such as "white head and white mouth" and bright red gill silk; The gills of the latter are visibly puffy and the gills are dark blue.

Third, the identification of intestinal wall expansion of fish disease

Coccidiosis, lateral trematodiasis, Taeniasis Hsu, Taeniasis of Jiujiangtou, Echinoccus terrestriosis, Echinoderosis and Echinoderosis of Cyprinidia have symptoms of intestinal wall expansion or intestinal blockage to varying degrees.

Side breeding trematodiasis and Jiujiangtou taeniasis have obvious symptoms of not eating food with closed mouth and open mouth without eating, respectively. Coccidioides are mainly parasitic in bluefish.

Taenia sylvestris and Echinaceae carp parasitize only carp, but the latter are generally parasitic in the foregut, and in severe cases the intestinal tubes become inflamed, swollen and ulcerated, and the intestinal wall is perforated. Echinococcus mainly harms grass carp.

Fourth, the identification of fish diseases with scaly bulge symptoms

There are mainly carp euphoriasis and erectile scale disease. The degree of uplift of the scales of the former is larger, the parasitic elongated red nematodes under the scales, squeezed without standing water, the skin muscles of the parasitic part of the insect body are congested and inflamed;

The scales of sick fish suffering from vertical scale disease are erect like pineal spherical balls, and the edema at the base of the scales is translucent and small sacs, and the water is squeezed out.

Fifth, the identification of fish diseases that gather around the pool or hit the shore with their heads

This can be horse racing, flooding or fish poisoning caused by small trichoderma. Horse racing is only a wild swim around the pool, driving it away;

Pan ponds generally occur when there is no wind, it is stuffy, the temperature rises, the air pressure drops, the thunder does not rain or thunderstorms, and it occurs after midnight.

All the fish in the pond float on the surface of the water, breathing with their mouths open, or lying on the surface of the water or hitting the shore with their heads, in a state of dying; Trichoces microflora tends to have most of the fish swimming wildly.

Generally, the pond fish concentrate on the four corners of the pool, and disperse them, and when the disease is serious, the pond fish are almost concentrated near the surface of the water at the edge of the pool, with their heads facing the shore and stationary.

Sixth, the identification of "aconitum plague"

These include grass carp enteritis and bacterial gill disease. Common symptoms are a dark body color and a dark head.

The difference is that the abdomen of the fish suffering from enteritis is swollen and has erythema, the hand is soft to the touch, the anus is red and swollen, and there is a milky yellow mucus flowing out of the abdomen under light pressure;

The epidermis in the gill cap of fish with bacterial gill disease is often hyperemic. It is worth noting that these two diseases often occur on the same fish body.

7. The body surface is white

Musporidiosis, leukodermasis, powdery disease, melon worm disease, microsporidium disease, hook-and-mouse larval disease, three-generation insect disease and water mold disease all have varying degrees of white body surface symptoms, which are distinguished by:

(1) Small melon worm disease. The surface of the fish, fins or gills are covered with many white dot-like membrane pustules, and there are hyperemic red spots between the white spots in the near future, and the white spots disappear 2-3 hours after the death of the disease value.

(2) Micro-robe worm disease. The surface of the fish has white dots of different sizes and shapes, and there are gray-white sacs.

(3) Myxosporidium disease, emaciation of fish, black body color, solitary swimming or restless and wild swimming.

(4) Powdery mildew. The dorsal fin, tail fin and back of the diseased fish have appeared white spots successively, and as the disease worsens, the number of white spots gradually increases, and eventually spreads throughout the body, making the entire body surface like self-powder.

(5) Leukoderma. The white spot of the diseased fish only appears at the base of the dorsal fin or at the tail stalk, and the development of the disease is only the enlargement of the white spot itself, and finally appears as the white of the entire posterior skin bounded by the dorsal fin, the sick fish head down, the tail fin upwards, perpendicular to the water surface, and soon dies of illness.

(6) Water mold disease. The surface of the sick fish is as long as cotton flocculent hyphae, the sick fish is restless, the movement is abnormal, the skin mucus increases, the appetite is reduced or absent, and finally the weakening and death.

(7) Hook-and-mouse larval disease. The white dots appear triangular and slightly beige; If the pathogen parasitizes the gills, the gills are severely hyperemic.

(8) Three generations of insect diseases. There is a large amount of mucus on the surface of the sick fish, and it can be seen that the fine hairy worm body is moving on the skin, and there is a gray-white mucous membrane on the severe skin, which loses its original luster.

Eighth, the body surface, fins are congested and decaying

Fish diseases that manifest such symptoms are generally red skin disease, printing disease, fulminant haemorrhagic disease, and anchor head hyacinth disease.

(1) Red skin disease fish scales shedding, moth fins, local or most of the body surface bleeding inflammation.

(2) Fulminant hemorrhagic disease fish fin base hyperemia, mouth, jaw, ferocity or decay, orbit prominence or congestion, carp hemorrhagic decay and accompanied by body surface muscle decay.

(3) Printing disease is a red spot with fingerprints on both sides of the tail stalk or abdomen, and the muscles rot from the outside to the inside.

(4) Anchorhead loach disease is that some of the scales are inflamed and red, and there are needle-like insect bodies in the red and swollen area.

Nine, impatient, wild swimming, jumping

Fish diseases that manifest such symptoms are generally: madness disease, silver carp, Chinese bream, anchorhead loach, fish flounder and compound fluke disease. The differences are:

(1) Madness disease and silver carp both harm silver carp and bighead carp, and the spine of crazy disease fish is curved, and the entire tail is extremely upturned and exposed to the water, and the skull is yellow.

Swim wildly in the water and sometimes sink to the bottom of the water and sometimes surface; Silver carp Chinese bream fish spine does not bend, only the upper lobe of the tail fin is often exposed to the water surface, so it is also called "cocked tail disease", the diseased fish only whirl or swim wildly on the surface of the water. There are many white insect bodies hanging from the end of the lyre, also known as "gill maggot disease".

(2) Chinese gill only parasitizes the gills of grass carp and bluefish, and the diseased fish have the phenomenon of jumping uneasiness, which is different from the silver carp Chinese gill disease fish generally do not jump.

Both Chinese loach disease and phyllod disease have sharp swimming and jumping phenomena, but the latter is mainly diagnosed by crawling with round or oval body surface and flat body.

(3) Both anchorhead loach disease and compound chilicosis are manifested as irritability of sick fish, but the former body surface parasitizes needle-like worms, and when seriously infected, the fish body resembles a cloak;

The latter is struggling uneasily on the surface of the water, sometimes head down, tail up out of balance, the sick fish eyeballs are cloudy, severe when the crystals fall off, and it is also known as "cataract" and "eye loss".

10. Fish float on the surface

This is a common phenomenon of fish bubble disease, hypoxia and wilting disease, the difference is:

(1) Bubble disease is a fish body floating on the surface of the water and can not sink.

(2) Hypoxia floating head often occurs at night to early morning, or when the heat is hot and windless, and the thunderstorm is coming, the symptoms of taking oxygenation measures will disappear quickly.

(3) The body of the fish is dry and thin, the head is large and the tail is small, the back is like a blade, the slow movement is black, and the body is scattered and floating on the surface of the water.