What are the prevention and control methods for parasitic diseases in rice field eels?

Rice field eels have a very high probability of suffering from parasitic diseases, and outbreaks are more likely in high-temperature seasons. Although diseased eels rarely die, their growth rate is greatly affected, which seriously impacts the economic returns of farmers. Here, some prevention and control methods for parasitic diseases are introduced to farmers.

Acanthocephaliasis

1. Symptoms: Diseased eels show a severe loss of appetite or stop feeding, the body color turns bluish-black, and the anus becomes red and swollen. The parasite's proboscis penetrates the intestinal mucosa to absorb nutrients, causing inflammation of the intestinal wall. In severe cases, it can cause intestinal blockage or perforation, leading to death of the eel. The incidence rate is about 90%.

2. Prevention and control methods

① Thoroughly disinfect with quicklime, or drain the pond water before stocking eel fingerlings and expose it to prolonged sunlight to kill the intermediate hosts.

② Add 5-8 g of "Eel Parasite Clear" per 1 kg of feed, mix with feed and feed once a day; during the disease season, use once every 7-10 days.

③ For every 100 kg of rice field eels, use 10 g of 90% crystalline trichlorfon daily, mix into earthworms or freshwater mussel meat and feed for 6 consecutive days. At the same time, splash crystalline trichlorfon over the whole pond to make the pond water reach a concentration of (0.3-0.5)×10~6.

④ Mix 1.5% "Yuchongqing No. 1" into bait and feed for a 3-day treatment course.

⑤ For every 100 kg of rice field eels, use 0.2-0.3 g of mebendazole and levamisole, mix into bait and feed; repeat once in the same way after 2 days.

⑥ Bathe diseased eels in a 2 mg/L "Baichongke" solution for 5-10 minutes; add "Yuchongmie" No. 1 to the feed at a 4% inclusion rate and feed for 1 day. Feed the medicated bait in 2-3 portions, and stop feeding for 1 day before medication.

⑦ If complicated by enteritis, feed in combination with antibiotics.

Capillariasis

1. Symptoms: Diseased eels show reduced appetite, become emaciated, and often stick their heads out of the water, with the abdomen facing upward or rolling in a struggling manner. June to September each year is the peak season for capillariasis in rice field eels. It occurs mostly in soil ponds with high-density still-water culture, while it occurs less in cement ponds or brick ponds with flowing-water culture. The incidence rate is about 80%.

2. Prevention and control methods

① In winter, dry the pond and expose the pond bottom and walls to sunlight. Before stocking eel fingerlings, thoroughly clear the pond with 200 g of quicklime per cubic meter of eel pond to kill pathogens in the original pond.

② During the epidemic season, splash 0.3 mg/L crystalline trichlorfon over the whole pond, 1-2 times per month.

③ For every 100 kg of rice field eels, use 0.2-0.3 g of levamisole or mebendazole and feed for 3 consecutive days.

④ For every 100 kg of rice field eels, use 10-15 g of 90% crystalline trichlorfon daily, evenly mix into feed and feed for 5-7 consecutive days.

⑤ Bathe diseased eels in a 2 mg/L Baichongke solution for 5-10 minutes; add Yuchongmie No. 1 to the feed at a 4% inclusion rate and feed for 1 day. Feed the medicated bait in 2-3 portions, and stop feeding for 1 day before medication.

⑥ Soak veterinary trichlorfon tablets (0.5 g/tablet) in water, crush them, and mix into feed at 0.1%; feed for 6 consecutive days.

Leech disease

1. Symptoms: Leeches parasitize near the head of the rice field eel and on both sides of the body, feeding on the eel's blood. The epidermal tissue of diseased eels is damaged, causing bacterial infection, which makes the diseased eels move slowly, reduces appetite, affects growth, and can lead to death in severe cases.

2. Prevention and control methods

① Take care not to introduce parasite sources when adding water or transplanting aquatic plants such as water hyacinth.

② Splash 0.5×10~6 crystalline trichlorfon over the whole pond; the next day, replace part of the pond water and splash the same dose again; on the third day, completely replace the pond water.

③ Bathe diseased eels in 3% salt water or a 10 ppm copper sulfate solution for 5-10 minutes.

④ Soak diseased eels in a 5 mg/L potassium permanganate solution for half an hour, which has a relatively good therapeutic effect.