Fish Diseases and Management

2.2.14 Pathology in vessels and heart

1. Heart

It is the major component of circulatory system.

a) Oedemo:- Oedema due to cardiac failure, manifested clinically by swelling of the abdomen, exophthalmia and softening of the myotomal musculature, is common in a variety of fish diseases.

b) Myocardial necrosis (Myopathy)

Degeneration of muscle in the heart leads to loss of pumping efficiency of the heart. This necrosis is due to bacterial or viral infection on the tissue.

C) Nutrition deficiency of vitamin E gives rise to nutritional myopathies, where cardiac muscle undergoes  atrophy with loss of striations and eosinophilia and coagulative necrosis of the ventricular myocardium.

2) Vessel

a) Fibrosis

Fibrius tissue gets deposited in the internal area of the blood vessels increasing the thickness of blood vessels and  resulting in narrowing of the lumen.

b) Punctate haemorrhages

Small holes or pores in the damaged area of capillaries leads to slow loss of blood from capillaries.

c) Peripheral circulatory failure

It results from excessive destruction of the osmotic barrier of the skin. When the capillaries are exposed to the aquatic environment, the difference in osmotic pressure may result in both inflow of water from exterior and loss of tissue fluids in case of fresh water fishes.

d) Endarteritis obliterans:- It is a frequently observed histopatholgical lesion in healing wounds in which degeneration of the media of larger vessels occur resulting in loss of potency.

Rhabdo viruses are primarily known to affect the circulatory system such as heart and endothelial tissue of the capillaries.