Male reproductive organs

• The male fishes have a pair of testes and a pair of sperm ducts.
• These are no copulatory organs in fishes, except shark, 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 bladder by means of 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 posterior end of testis, a sperm duct or vas deferens arises communicated with their respective testis by means of several fine ductless that finally opens into the urinogenital sinus/opening.
• Seminal vesicle is absent in teleost with some exception (e.g. clarius and Heteropneustes).

b) Sperm duct:

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