VPP 322: Aquatic Animal Diseases, Health Care and Management (1+1)

DIGESTIVE PHYSIOLOGY OF FISHES

• Physiology may be defined as the branch of biology that deals with life process. Physiology is the regulation of function, how they are correlated and integrated into a smooth – functioning of the organisms.

Digestive physiology of fishes

• The digestive system consists of alimentary canal and its associated glands. The digestive tube also contains numerous intramural glands which provide the tube by lubricating mucus enzymes and water etc. The extramural glands are liver, pancreas and gall bladder.
• The liver is present in all fishes. The pancreas which is exocrine and endocrine organ may be a discrete organ or it may be diffused in the liver or in the alimentary canal. In sharks and rays (elasmobranchii) pancreas is relatively compact and usually well developed as separate organ, often two lobed, but in teleosts, the pancreas is diffused in the liver to form hepatopancreas. It is also diffused in the alimentary canal in few fishes. It is also present in mesenteric membranes surrounding the intestine and liver. The gall bladder is vestigeal in deep sea fishes but it is prominent in other fishes.
• While passing through the alimentary canal, the food is broken down physically and chemically and ultimately solubilized so that degraded products can be absorbed.