Detailed Explanation of Common Disease Prevention and Control Methods for Fish and Crabs, a Must-Read for Farmers

I. Grass carp hemorrhagic disease

Symptoms: bleeding in the fins, mouth, eye sockets, muscles, and intestines, partially or entirely bright red.

Prevention and control: 1. Splash dibromohydantoin or chlorine dioxide over the entire pond, using 200 grams of dibromohydantoin or chlorine dioxide per 1 mu of water surface with a depth of 1 m. Apply once more after 2-3 days. 2. Mix Yu'erkang into bait and feed, mixing 1 kg of Yu'erkang per 50 kg of feed, and feed continuously for three days. 3. Mix Suke into bait and feed, mixing 50 grams of Suke per 50 kg of feed, feeding once a day, with three consecutive days as one treatment course. If combined with external use of dibromohydantoin and chlorine dioxide, the effect will be even more pronounced.

II. Fish bacterial gill rot

Symptoms: the gill filaments rot and carry sludge; in severe cases, the gill filament cartilage is exposed, and the inner epidermis of the operculum is eroded, forming a transparent "small window" (commonly known as an open skylight).

Prevention and control: 1. Splash dibromohydantoin or chlorine dioxide over the entire pond, using 200 grams of dibromohydantoin or chlorine dioxide per 1 mu of water surface with a depth of 1 m. 2. Splash Yuxia Junbijing over the entire pond, using 200-300 grams per 1 mu of water surface with a depth of 1 m. Apply once a day, for two consecutive applications.

III. Fish enteritis disease

Symptoms: the anus of the diseased fish is red, swollen, and protruding, there are red spots on the abdomen, and the fish loses its appetite shortly after onset.

Prevention and control: 1. Mix garlic paste into bait and feed, mixing 50 grams of garlic per 500 grams of feed, feeding once a day for 3 consecutive days. 2. Mix 0.1 grams of oxytetracycline per 1 kg of feed and feed, feeding once a day for 3 consecutive days.

IV. Fish putrid-skin disease (red-skin disease, stamp disease, white-skin disease)

Red-skin disease symptoms: the fish body surface bleeds and becomes inflamed, scales fall off, most obviously on both sides and the abdomen of the fish body, the fin bases are congested, the fin tips rot and become incomplete, and the fin rays split.

Stamp disease symptoms: round red spots appear on both sides near the anal opening of the diseased fish, shaped like a red seal, with surrounding congestion and inflammation.

White-skin disease symptoms: in the early stage of onset, a white spot appears at the caudal peduncle of the fish; as the disease progresses, the white spot can spread to the entire skin between the dorsal fin and the caudal fin; in severe cases, the caudal fin rots off, the fish hangs vertically in the water with its head downward, and soon dies.

Prevention and control: splash dibromohydantoin or chlorine dioxide over the entire pond, using 200 grams of dibromohydantoin or chlorine dioxide per 1 mu of water surface with a depth of 1 m.

V. River crab tremor disease (ring-leg disease)

Symptoms: the diseased crab's appendages curl inward, it stands unsteadily, moves weakly, has difficulty turning over, trembles all over continuously, then stops eating, and dies from fluid accumulation in the body.

Prevention and control: splash dibromohydantoin or chlorine dioxide over the entire pond, using 200 grams of dibromohydantoin or chlorine dioxide per 1 mu of water surface with a depth of 1 m, for 2-4 treatment courses.

VI. River crab ciliate disease

Symptoms: many brown or yellow-green fuzz attaches to the body surface and gills of the diseased crab, and the parasites can be found under microscopic examination.

Prevention and control: splash Xianchong Shaxing, Xiaxie Shachongjing, and other drugs over the entire pond, splashing 250 grams of Xianchong Kexing or Xiaxie Shachongjing per 1 mu of water surface with a depth of 1 m.

VII. River crab enteritis disease

Symptoms: the diseased crab has poor digestion, gastrointestinal inflammation, and bloating; when the abdominal flap is opened and the anus is gently pressed, yellow mucus can be seen flowing out.

Prevention and control: 1. Add 50 grams of garlic per 500 grams of feed, once a day for 3 consecutive days. 2. Add 0.1 grams of oxytetracycline per 1 kg of feed, once a day for 3 consecutive days.