Control technology of cross-breeding silver crucian carp fingerworm disease in pond culture in Yancheng, Jiangsu Province
_Hu Huarong
The heterogeneous silver crucian carp belongs to the order Cyprinid, carp family, carp subfamily, crucian carp genus, is the use of triploid square silver carp (mother) and diploid Xingguo red carp (father) to artificial hybridization method to induce the eggs of founder silver carp for female nuclear development and develop. The heterogeneous silver crucian carp has the characteristics of fast growth, large individual and strong resistance to stress, and has become a major breeding species in Binhai County. In recent years, with the expansion of the scale of farming, the incidence of ringworm disease has been high, causing great losses to farmers. In order to effectively prevent the occurrence of ringworm diseases in the heterogeneous silver crucian carp, the control technology of ringworm disease was preliminarily discussed.
1 Test method
1.1 Materials
Heterogeneous silver crucian carp.
1.2 Time and Place
In 2020, Wuxun Town, Binhai County.
1.3 Pond conditions
Test ponds A and B, control ponds C. The area is 0.334 hm2, the water depth is 1.5 to 2 m, and the bottom mud thickness is 25 to 30 cm.
1.4 Clear ponds, fill water and disinfect
(1) Ponds A, B. 15 days before stocking, use 80 kg of quicklime per 667 m2 and clear the pond dry (leave a little water, water depth 6 to 10 cm). After clearing the pond 7 d, water injection 80 ~ 100 cm. 5 days before stocking, disinfect the newly injected water with 70 mL of compound iodine per 667 m2.
(2) Pond C. Pond disinfection.
1.5 Fingerling disinfection and stocking
Before stocking, soak in 10 to 20 g/m3 of bleaching powder (containing 28% of available chlorine ≥) for 20 min.
The stocking size of the heterogeneous silver crucian carp is 60 g/tail, 1 000 per 667 m2, and the stocking of silver carp and bighead carp summer flowers with a stocking size of about 3 cm is also stocked with 2 000 and 500 per 667 m2, respectively. The stocking pattern is the same in all three ponds.
1.6 Activation and use of Bacillus
Bacillus is activated with 50 times the pond water for 4 h. Choose a sunny morning and sprinkle every 10 d at 125 g per 667 m2. Turn on the aerator when spilling, which is conducive to the rapid reproduction and growth of live bacteria.
1.7 Preparation and feeding of medicinal bait
Select an algae-derived amino solution that can enhance immunity, and add it to the compound pellet feed at a rate of 0.2% to make a bait to enhance immunity. Feed every 10 days for 3 to 5 days.
1.8 Regular insecticide
Pond A is sprinkled with the insecticide mebendazole every 20 days, and mebendazole is applied after pond B heterogeneous crucian carp become ill for 7 d (dead fish appear).
2 Experimental results
The results of the test in ponds A, B, and C are shown in Table 1, and the incidence of the isolated silver crucian carp in the test is shown in Table 2.
Table 1 Test results of ponds A, B and C (1)
(1) + indicates that the treatment was taken; - indicates that the treatment was not taken; × indicates that the treatment was taken after 7 d of the onset of illness (dead fish).
Table 2 Incidence of the isolated silver crucian carp tested
Pond A adopted technical measures such as pond disinfection, fish fingerling disinfection, application of bacillus, feeding of medicinal bait, regular insecticide, and sprinkling of compound iodine, and the heterogeneous silver crucian carp did not occur during the entire feeding period.
Pond B only took two conventional technical measures of pond disinfection and fish fingerling disinfection, and after 7 days of illness (dead fish appeared), mebendazole was sprinkled, and bacillus was not administered, bait was fed, and compound iodine was sprinkled, and the onset of the disease began on June 25 and continued for 10 to 16 days, with a mortality rate of 36%. Pond C did not take any precautions, and the onset of the disease began on 5 June and continued for 20 to 30 days, with a mortality rate of up to 71%. Pond B and C heterogeneous silver crucian carp are both affected by ringworm disease and gill rot.
3 Discussion
3.1 Effect of comprehensive disease prevention measures
The prevention and control of fish diseases is an important guarantee for the cultivation of heterogeneous silver crucian carp to obtain high and stable yields. The test results show that in addition to thoroughly cleaning the pond with drugs such as quicklime and bleach powder, the fish species should be strictly disinfected when they enter the pond, the water quality should be adjusted, the scientific feeding should be adhered to, and the robust fish species should be strictly selected. Pond A adopted comprehensive disease prevention measures, and the disease prevention effect was remarkable during the whole rearing period of heterogeneous silver crucian carp.
3.2 Effects of conventional disease prevention measures
Pond B only adopted the usual disease prevention measures of clearing the pond and disinfecting the fingerlings, and the onset time was delayed by 20 days compared with pond C. It shows that conventional disease prevention measures also have a certain anti-disease effect.
3.3 Efficacy of mebendazole
Pond B was only administered to mebendazole 7 d of the onset of illness (the presence of dead fish), which shortened the duration of disease by 10 to 14 days compared with pond C and reduced mortality by 35% compared with pond C. It shows that the combination of mebenzimidazole for preventive medication and actual treatment has a good effect.
4 Conclusion
In the process of heterogeneous silver carp breeding, we should properly do a good job in disease prevention and control, and implement the fish disease prevention and control principle of "early prevention without disease and early treatment of disease". Actively adopting comprehensive disease prevention measures is the key to the prevention and control of interborn silver crucian carp ringworm disease.