Mechanism of Respiration in Fishes

Respiration in fish takes place with the help of gills. Most fish possess gills on either side of their head.

Gills are tissues made up of feathery structures called gill filaments providing a large surface area for gas exchange. A large surface area is crucial for gas exchange in aquatic organisms as water contains very little amount of dissolved oxygen. The filaments in fish gills are organized in rows in the gill arch. Each filament comprises lamellae, which are discs supplied with capillaries. Blood moves in and out of the gills through these small blood vessels.