1. FUNGAL DISEASES

2. Cotton wool disease Causative agent – Saprolegnia
opportunistic pathogenic fungi affecting tropical fishes and fish eggs
Symptoms
greyish white, cotton-like growths on the skin, gills, eyes, or fins that may invade deeper tissues of the body.
preventive measures
removal of predisposing causes, e.g. inadequate sanitation,
excessive chemical treatment, or the presence of dead, infected fish and decaying organic material.

3. Ichthyophonus hoferi
This fungus causes an internal infection and is generally chronic and progressive.
Preventive measures
removing infected fish and avoiding feeding raw fish products.
Iodophors of varying iodine concentrations are used to prevent mycotic infections of nonfood-fish eggs, which can be disinfected by a 100 ppm iodine bath for min.
Formaldehyde, up to 2,000 ppm for 15 min, can be used to treat eggs

4. Larval mycosis in shrimps
Causitive agent-Lagenidium sp. Sirolpidium sp. and Haliphthoros sp
filamentous non-septate and coenocytic fungi
Affected larvae appear opaque followed by sudden mortality
Larval stages are highly susceptible
Black gill disease of larvae is caused by Fusarium sp. in shrimps.
Saprolegnia and Leptolegnia cause dark necrotic lesions on shrimp exoskeleton and cause gradual mortality.

5. Epizootic Ulcerative Syndrome (EUS)
Cause damage to a wide variety of fishes (most affected are murrels) but chineese carp and tilapia relatively resistant
Causitive agent-Aphanomyces invadans.
Infection starts as a red spot in the skin then it eventually becomes an ulcer and finally resulting in erosion of ulcerative area.
Disgnosis:-Grocott’s stain is used for fungal staining. It gives black colouration in the fungal hyphae.
A. invadans has the ability of penetrating the body of the fish using the proteolytic enzyme
It causes mortality by two means
(i) by invading fungus
(ii) osmoregulatory failure of invaded area

6. Contd….. Control Measures
In the initial stage, application of lime and sodium chloride treatment was found to be effective.
CIFA produced a mixture of CIFAX, for controlling EUS but not much standardized.
Treating the water with chlorine before letting in to the pond, avoidance of water use from large water body with improper water quality, use of filters in water channels to avoid wild fish entry and preventing the entry of predatory birds are central to disease management strategy.