Course Content
Introduction
Definition of fish, fishes, Fisheries and Aquatic habitats, Economic importance of fish
0/3
Introduction
Economic importance of fish
Harm caused by fish
Taxonomy
Classification of Super class Pisces up to family, general characters of classes, Nomenclature of classes, family, genera and species of fishes, Identification of fishes of Nepal: Zoological key, illustration, specimens, experts, economically important food fishes of Nepal and their classification with characters
0/7
General characteristics of fish
Classification of fishes
Class 1. Chondrichthys or Elasmobranchi
Class 2. Holocephali
Class 3. Dipnoi
Class 4. Osteichthyses a Telostomi
Class Teleostomi is divided into two sub-classes
Morphology and anatomy of fish
External features of different kinds of fish, Structure and functions of skin, Structure and function of Scales and fins, Location and functions of different internal organs
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External features of different kinds of fish
Skin: Structure and Functions
Functions of skin
Structure of Scales
Types of scales
Function of scales
Structure of fins
Origin theory of fins
Types of Caudal fin
Fin rays
Spines and rays
Types of fins
Location and functions of different internal organs
Types of Caudal fin
Function of fin
Digestive system
Structures of alimentary canal in different fishes, Mechanism of digestion (digestive glands, enzymes)
0/5
Introduction
Classification of fish  based on feeding habit
Digestive parts of fish
Digestive glands
Mechanism of digestion
Respiratory system
Structure of gills and accessory respiratory organs, Mechanisms of respiration
0/8
Respiratory organs of Cyclostomes
Respiratory organs in elasmobranchs
Gill
Mechanism of respiration in fish
Gills in Protochordates
Gills of bony fishes
External gills
Accessory respiratory organs in fishes
Reproductive system
Structures of gonads, Mechanism of gonad development (Spermatogenesis, Oogenesis)
0/8
Types of reproduction in fish
Reproductive system in fish
Male reproductive organs
Mechanism of Spermiogenesis
Seasonal morpho-histological changes of testes
Female Reproductive organs
Mechanism of Ovary Development
Processes in reproduction
Circulatory and Excretory system
0/4
The circulatory system in fish
Parts of heart
Circulatory mechanism
Excretory system of fish
Endocrine system
Endocrine glands, Hormones and their actions
0/13
Introduction
Pituitary Glands
Anatomy of the Pituitary Gland
Part and division of pituitary, their cell types, secretions and action of their hormones
Use of pituitary hormones in induced breeding
Thyroid Gland of Fishes
Hormones of Thyroid Gland
Adrenal gland
The Ultimo-Branchial Gland
Intestinal Mucosa
Islets of Langerhans
Pineal Organ
Urophysis
Nervous system
Structure of brain, Peripheral nervous system
0/3
Introduction
Divisions of Brain in Fishes
Peripheral nervous system
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About Lesson

Islets of Langerhans:

  • In some fishes like Labeo, Cirrhinus, and Channa small islets are present which are separate from the pancreas and are found near the gall bladder, spleen, pyloric caeca, or intestine.
  • Such islets are often referred to as principal islets.
  • In fis,h the islets are big and prominent and consist of three kinds of cells.

(i) The beta cells which secrete insulin and take aldehyde fuschin stain,

(ii) Another type of cells are alpha cells, which do not take aldehyde fuschin stain and have two types, A1 and A2 cells, which produce glucagon. The function of the third type of cells is not known. Insulin is secreted by beta cells and regulates the blood sugar level in fish.

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