RESPIRATION IN FISHES -

• Respiratory organs are gills. In elasmobranchi 5-7 pairs of gills present, spiracles present.
• In Teleostomai 4 pairs gills present, covered by operculum. Respiration by gills is brachial respiration.
• Each gill is made up of two rows of gill filaments that project from the pharyngeal wall into the gill chamber.
• Each gill filament leave a series of thin, leaf like gill lamellae.
• A gill lamellae contains a network of capilalries covered by a thin epithelium.
• For brachial respiration water enters through mouth.