Prevention and control of common diseases of cultured river crab

1. Carapace ulcer

1. Symptoms: the exoskeleton of the crab has ulcerative damage, there are many brown spots on the carapace in the early stage, the center of each spot is reddish and concave, the edge of the spot is black in the late stage, the ulcer deepens in the center, the carapace is invaded into a hole, and the muscle or skin membrane can be seen. Eventually lead to the death of river crabs.

two。 Prevention and treatment: (1) avoid crab body injury as far as possible. (2) keep the water quality fresh and fresh, and make the bottom of the pond have about 10 cm of soft mud. (3) sprinkle the whole pool with 15 × 10E-6 quicklime solution or 1 × 10E-6 furazolidone solution. Sprinkle every 7 to 10 days for 2 to 3 times. (4) 0.1 grams of oxytetracycline or erythromycin per kilogram of crabs were fed for 7 days.

Black Gill disease

The main results are as follows: 1. The infection site of the symptom is mainly the Gill. When the disease is mild, the Gill filaments are dark gray or black, and when the disease is severe, the Gill filaments are all black. The sick crabs move slowly and have difficulty breathing.

2. Prevention and treatment methods: (1) remove the residual bait every day, replace the stagnant water in time, and remove the diseased crabs; (2) prevent the whole pond from sprinkling raw lime solution with a concentration of 15 × 10E-6~20 × 10E-6 (3) sprinkle it continuously for 2 times with a concentration of 20 × 10E-6 during treatment. (4) the diseased crab can be placed in furanone solution with the concentration of 2 × 10E-6~3 × 10E-6 and washed for 3 times for 4 times for about 20 minutes each time.

3. Edema disease

1. The abdominal navel and dorsal shell of the diseased crab were swollen and transparent, refusing to eat to death.

two。 Prevention and control methods: (1) in the process of breeding, minimize the disturbance to them. (2) often add fresh water and feed more fresh feed and fresh vegetable leaves. (3) the disease was treated with oxytetracycline or furacilin at the concentration of 0.5 × 10E-6~1 × 10E-6 or furazolidone at the concentration of 0.1 × 10E-6~0.2 × 10E-6.

IV. Ciliosis

1. At the initial stage of symptoms, there are many yellowish green or brown villi on the crab body surface, slow movement, insensitive antennae, slippery body surface appendages, and microscopic examination shows that many ciliated parasites are attached.

two。 Prevention and control methods: (1) clear the pond thoroughly with quicklime before stocking. (2) the seedlings were soaked in zinc sulfate solution of 20 × 10E-6 concentration for 1 hour before stocking. (3) the whole pool was sprinkled with zinc sulfate of 3 × 10E-6 concentration.