Examination of sick fish

The fish were examined for symptoms, symptoms, pathogen identification and histopathological examination.
1 external symptoms of examination
The external symptoms of the sick fish were examined mainly by the visual identification of symptoms and pathogens. In general, the symptoms of different pathogens are different from the symptoms caused by fish. The main pathogens are divided into two major categories of microbial and parasitic. The parasite that causes the disease often show excess mucus, bleeding, punctate or massive cyst and other symptoms, especially some large parasites, such as worms, crustaceans and size larger protozoa (such as sticky robe worm cyst, etc.), with the naked eye can see that. The disease caused by pathogenic microorganisms, more performance for the fish body hyperaemia, inflammation, abscess, decay, fin erosion, vertical scales and other symptoms.
According to the general order of the site is from the surface to the gills,
(1) surface from aquaculture fish out just dead or dying of disease fish and placed in white porcelain or fish plate, along the head, drive cadres to tail, namely according to the sequence of mouth, eyes, operculum, scales, fins and friends careful observation,
Some of the major pathogens, such as water mold, nematodes, anchor head), louse, glochidium and sticky Cryptosporidium cysts etc., easily detectable. But some small pathogens, the naked eye can not see, then should be judged according to the symptoms. Such as car rotifers, wave fish Bodo, Chilodonella, Ichthyophthirius, three generations of insects, such as caused by the symptoms, the general will lead to the excessive secretion of mucus of fish body surface, sometimes mixed with sludge, or is the head, mouth and node end rot, but Jing strip base department generally does not appear congestion phenomenon. The complex mouth of the fluke disease, the performance of the eyeball, the ax, there is a cataract. Grass carp hemorrhage, bleeding in the oral, head, eyes to sleep, fin base, jaw, operculum and abdominal occasional light red blood spots. Bacterial red skin disease, performance for shedding scales, skin congestion; furunculosis is in lesion inflammation and abscess; leukoderma is lesion inflammation, reduce mucus, rough to the touch; print disease is in massive erosion of decay for the disease. However, some symptoms, including symptoms of skin, gill disease, different disease symptoms are basically the same situation, such as red skin disease, gill rot disease, enteritis and other parts of the bacterial disease are symptoms of fin base congestion and moth fin, so fish disease diagnosis, unlike the diagnosis of human disease that interrogation, only through detailed investigation and comprehensive symptoms are analyzed, in order to make the accurate diagnosis and correct.
(2) the examination of the gill, with emphasis on the gill filaments. First observe the gill cover is opened inflation, then used a pair of scissors to the operculum to cut, the observation of the gill lamellae color is normal, mucus, gill filament end whether there enlargement decay. Bacterial Gill Rot Disease gill decay in the end, many mucous; Branchiomycosis gill lamellae of color than normal fish gill lamellae of the color white, tinged with blood red dots; if wave fish Bodo, cryptobia, Trichodina, Chilodonella, Dactylogyrus and insects, such as parasitic, gill plate more mucus; if Chinese Sao, narrowly abdominal), single insects and some Dactylogyrus and myxospore insect cell capsule and parasitic, gill enlargement, opercular swelling and other symptoms.
Internal symptom check
Check fish tissue disease mainly to gut check, the fish on the side of the abdominal wall cut off, the first observation of whether there is ascites and visible to the naked eye fish strange, nematodes, ligula intestinalis and other parasites; carefully observed the internal appearance is normal; then with a pair of scissors from by the throat of the foregut and by the anus intestine cut, remove the internal organs, placed in a white porcelain, one by one from liver, gall bladder, bladder and other organs. Finally, the intestinal once the gut and hindgut cut open, divided into before, during and after the three sections, gently put food and feces in the intestinal tract removed, carefully examined. Intestinal parasitic trematodes, cestodes, nematodes can be easily seen; bacterial enteritis will exhibit intestinal hyperemia and inflammation; hemorrhage of grass carp is intestinal or local is bright red bleeding, enteral without food, but the intestinal wall is still relatively strong, erosion; coccidiosis and sticky Cryptosporidium disease is in the intestinal wall with sheets or dilute the white dots scattered. Other internal organs, if not found in the appearance of symptoms, the general can no longer check.
Do check the detailed record, for fish disease diagnosis provide correct basis, and fish disease diagnosis and improve farming techniques accumulated data and experience.
3 pathogen identification
Pathogen identification is generally used in optical microscopy, and the anatomy of the disease fish to do a deeper pathogenic, pathological examination. With the exception of some of the more obvious and fish disease condition and relatively simple, by visual inspection can accurate diagnosis, the general must be microscopy can be diagnosed.
The examination of the lesions was carried out in the selected area, and the location and sequence of the examination were the same as the target.
Check method is from the lesion site from small amounts of tissue or mucous placed slide on, such as skin and gill tissues or mucus, plus a small amount of ordinary water, internal organs should add a small amount of normal saline (0.85% saline water), and then covered with coverslips, and slightly flattened, placed under the optical microscope observation. In order to accurately, at least 3 different points of each lesion were examined.
When in water bodies of the same breed, there are more than two kinds of fish, you need to to various pathogens and intensity of infection and the fish in the degree of damage were compared and analyzed, identified the major and minor pathogens, in order to facilitate the development of therapeutic measures.

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