Non-infectious disease or Disease of miscellaneous origin1.pptx

Non-infectious diseases of fishes

1. Non-infectious disease or Disease of miscellaneous origin Dilip Kumar Jha, PhD. Professor Department of Aquaculture Faculty of Animal Science, Veterinary Science & Fisheries Agriculture & Forestry University, Rampur, Chitwan Former Director , C urriculum D evelopment C enter, AFU 1

2. Asphyxiation Is caused due to low DO content of water Frequently a problem during summer Usually seen in fish ponds with a heavy algal bloom The minimum acceptable level of DO is 5 ppm 2

3. Asphyxiation (contd.) Signs: Suffocation, Fishes come to water surface, Gulp air bubbles very frequently Congregate at water inlet Mouth wide open Opercula raised and gills spread wide apart 3

4. Asphyxiation (contd.) Management: Use of aerators Surface agitation Increase inflow to aerate water Thinning the population of fishes Methods are used singly or in combination to remedy the problem 4

5. Super-saturation of gases or gas bubble disease or gas embolism Occurs when excess of gasses in the water Saturation level of above 110% Under pressure increases solubility of all gases 5

6. Super-saturation of gases or gas bubble disease or gas embolism.. Signs: Observable gas bubbles in the body cavities; often behind eye or between surface tissues (opercula or lips) Often swim at an angle of 45 with head pointing down Prevention: Proper installation of water supply Differentiate between asphyxiation and super-saturation of gases 6

7. Aflatoxin /Dietary toxins Poison found in oil seeds (cotton, wild palm MOC,GNC, maize) because of being stored in damp condition and the fungus Aspergillus flavus being allowed to grow on them Causes cancer of the liver and destruction of the blood forming tissue of the kidney 7

8. Mechanical trauma Can be caused by netting, handling operation, grading, holding and sorting of brood fish, stripping eggs and milt Thus resulting in injuries and invasion of pathogens Leads to death or subsequent infection 8

9. Temperature Metabolism of fish is directly related to the temperature of water Low temperature reduces metabolic activity Each fish species has an inherent temperature range Cold water fishes ( sacrophilic ) cannot survive >25 C but existence limited by 20 C Warm water fishes ( thermophilic ) live continuously at 33 to 35 C but their metabolism gets much reduced at 20 C while some are even incapable of living at 5 to 10 C 9

10. Temperature Cool water ( mesophilic ) fishes are capable of living at a broad range of temperature ( 5 to 30 C) and may complete reproduction between 10 to 30 C 10

11. Thermal trauma Changes beyond normal range cause thermal trauma which includes effects on cardio-vascular system and nervous system Changes in the colloidal state of proteins Reduction and cessation of enzymatic activities Permanent impairment of body functions Burning and ulceration on the top of head and fins 11

12. 12 Protection from thermal trauma: M aintaining required water levels Providing shade

13. pH Acceptable limit of pH for most fishes is about 6.8 to 8.6 (It may be 6.2 -9.2 for short duration). Excessively high or low pH may be responsible for Stress Increased toxicity of the substances Frantic fishes And fishes seeking the shoal areas -The fishes even become beached in an attempt to remove themselves from irritating effects on skin and gills -Skin and fins may become erythemic 13

14. Nutritional deficiency Nutritional deficiency will result in reduced yield of fertile egg, poor fry with a reduced yolk sac and low survival ability. Similarly, malnutrition, which is excess or deficiency of nutrients, will impair growth and result in poor food utilization and lower resistance to diseases etc Prevention: By using feed having standard quality and by proper feeding 14

15. Nutritional deficiency Add more on deficiency from different nutrients , minerals and vitamins While elaborating mention references 15

16. Thanks for your attention 16