Male reproductive organs

• The male fishes have a pair of testes and a pair of sperm ducts.
• There are no copulatory organs in fishes, except sharks, claspers act as copulatory organs.
• So, in such fishes, internal fertilization takes place and gives birth to young ones.

a) Testes:

• The reproductive organs of male fish consist of a pair of testes which are elongated and flattened structures, situated on either side, ventral to the kidneys in the posterior region of the abdominal cavity just beneath the air bladder.
• The testes remain attached to the body wall and the air bladderusingf mesorchia.
• The testis has two major functions, the production of gamete and another function is the production of steroids.
• Most often, the testes are creamy-white but in Labeo rohita they are pinkish and smooth.
• From the posterior end of the testis, a sperm duct or vas deferens arises communicated with their respective testis using several fine ductless that finally open into the urinogenital sinus/opening.
• The seminal vesicle is absent in teleost with some exceptions (e.g. claims and Heteropneustes).

b) Sperm duct:

• From each testis sperm ducts or vas deferens originate.
• In some fishes, mesonephric ducts unite with the testis to form vas deferens and vasa efferentia.
• In shark fishes sperm duct opens into another chamber kasa asa seminal vesicle.
• The seminal vesicle is thickened and often has more diameter than the sperm duct.
• The sperm is stored for short periods but it is absent in teleosts.
• The sperm ducts from each testis often join to form a common duct and open through the genital pore lying between the anus and urinary aperture.