COMMON INFECTIOUS DISEASES IN FRESHWATER FISHES IN INDIA – PATHOLOGY AND MANAGEMENT
Ishita Srivastava1, Sarjna Meena2, Sachin Kr Meena3, Manisha Meena4
1,3,4M.V.Sc Scholars
2Assistant Professor
Department Of Veterinary Pathology, PGIVER, Jaipur, RUVAS
INTRODUCTION
Aquaculture is a fast-growing food production sector with 122.5 million tonnes (MT) total of production globally in 2020 (SOFIA, 2022). In which, Indian aquaculture production is pegged at 8.64 MT in 2020 (SOFIA, 2022). The surging demand for fish, coupled with a decline in marine catches, has exerted significant pressure on the aquaculture industry, driving the need for intensified operations.
Although several treatment methods are available, they can be difficult and often impracticable for ponds containing a large number of fish. The most efficient technique to prevent the spread of disease is the removal and extermination of infected fish from the pond . Fish diseases are one of the major constraints in aquaculture, leading to heavy economic losses due to mortality, reduced growth, and poor market quality. Among various etiological agents, bacterial and viral pathogens play a crucial role in disease outbreaks, especially under intensive culture systems. Understanding their etiology, age susceptibility, lesions, clinical signs, and preventive strategies is essential for effective disease management.
Bacterial Diseases of Fishes
1.Aeromoniasis (Motile Aeromonas Septicemia)
Etiology: Aeromonas hydrophila, A. sobria, A. caviae.
Age group affected: All age groups; more severe in fingerlings and stressed adult fishes. Important lesions: Hemorrhages on body surface, ulcerative skin lesions, fin rot, congested liver and kidney, ascites.
Important symptoms: Lethargy, loss of appetite, hemorrhagic septicemia, exophthalmia.
Prevention and control: Good water quality, avoidance of overcrowding, stress reduction, use of probiotics and approved antibiotics after sensitivity testing. Vaccination: Inactivated (killed) bacterins used in some cultured fishes
- Columnaris Disease
Etiology: Flavobacterium columnare.
Age group affected: Fry and fingerlings mainly; adults also affected.
Important lesions: Greyish-white patches on skin and gills, gill necrosis, erosion of fins. Important symptoms: Respiratory distress, sluggish movement, high mortality in young fish.
Prevention and control: Proper sanitation, water management, potassium permanganate or lime treatment.
Vaccination: Experimental vaccines under development; limited commercial use.
- Edwardsiellosis
Etiology: Edwardsiella tarda.
Age group affected: Mostly fingerlings and adult fishes. Important lesions: Internal hemorrhages, abscesses in muscle, enlarged spleen and kidney. Important symptoms: distension.
Prevention and control: Biosecurity measures, pond hygiene, antibiotic therapy. Vaccination: Inactivated vaccines available for some species
Viral Diseases of Fishes
1.Koi Herpesvirus Disease (KHVD)
Etiology: Cyprinid herpesvirus-3.
Age group affected: Juveniles and adults of koi and common carp.
Important lesions: Severe gill necrosis, skin lesions, internal organ congestion. Important symptoms: Gasping at water surface, lethargy, high mortality
Prevention and control: Quarantine, movement restriction, biosecurity.
Vaccination: Live attenuated and temperature-based vaccines used in some countries.
- Viral Hemorrhagic Septicemia (VHS)
Etiology: Viral hemorrhagic septicemia virus (Rhabdovirus). Age group affected: Mainly juveniles; adults may act as carriers.
Important lesions: Widespread hemorrhages in muscle and internal organs, pale liver. Important symptoms: Darkening of body, exophthalmia, abnormal swimming.
Prevention and control: Strict biosecurity, disinfection, control of fish movement. Vaccination: DNA and inactivated vaccines under research and limited application.
- Infectious Pancreatic Necrosis (IPN)
Etiology: Infectious pancreatic necrosis virus (Birnavirus).
Age group affected: Fry and fingerlings, especially salmonids.
Important lesions: Pancreatic necrosis, catarrhal enteritis, ascites. Important symptoms: Sudden mortality, spiral swimming, anorexia.
Prevention and control: Egg disinfection, use of virus-free broodstock.
Vaccination: Oral and injectable vaccines used in some aquaculture systems.
Conclusion
Bacterial and viral diseases of fishes pose a serious threat to sustainable aquaculture. Early diagnosis, understanding of etiological agents, and recognition of key lesions and symptoms are essential for effective disease control. Preventive measures such as good management practices, biosecurity, and vaccination play a vital role in reducing disease incidence.
