Prevention and Control Techniques for Several Common Diseases in Largemouth Bass Farming
Largemouth bass has extremely strong resistance to disease, so the proportion that falls ill is quite low. The diseases known so far are the following:
1. Anchor worm disease (Lernaea disease): this disease occurs only in a few individuals, and the parasitic sites are mostly at the base of the dorsal fin or anal fin, and the tail end; the affected area often has blood stasis, and the sick fish has a slightly poorer appetite. The treatment method is to catch the sick fish, pull out the anchor worms, then disinfect the wound with 10 mg/L potassium permanganate, or increase the exchange of new water to prevent its spread.
2. Saprolegniasis: the main cause of this disease is that when the body has a wound or scales have fallen off, the water temperature drops, and it is infected by water mold and develops the disease. The affected area has cotton-like white fuzz; when the disease is severe, the fish loses appetite and eventually dies. The preventive method is to avoid catching fish when it is cold, or when catching, try to avoid injuring the fish body or causing scales to fall off. When this disease occurs, it can be disinfected with a 1 mg/L malachite green solution. But note that the disinfection time is inversely proportional to the water temperature: the higher the water temperature, the shorter the time required, and the lower the water temperature, the longer the time required. If the water temperature is about 20°C, the disinfection time is 15-20 minutes, once a day, for 3-4 consecutive days.
3. Blindness: mainly the eye membrane of the sick fish turns white and cloudy, making it unable to feed, and finally it dies. The cause is damage to the eyes during catching. Therefore, when catching, special care must be taken to prevent injury to the eyes.
4. Scoliosis: the fish body's vertebrae become abnormal and bent. The cause is not yet clear; it may be caused by abnormal division during the hatching of fertilized eggs, and there is no treatment method. Fish in this state grow quite slowly, so they are not suitable for farming and should be culled during farming.