Exchange of gases in fish is very efficient because of: the large surface area of the gills. the large surface area of the blood capillaries in each gill filament. the short distance required for diffusion – the outer layer of the gill filaments and the capillary walls are just one cell thick.
Answer:
Gills
Explanation:
In order to remove oxygen from the water, they rely on special organs called "gills." Gills are feathery organs full of blood vessels. A fish breathes by taking water into its mouth and forcing it out through the gill passages.
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How Do Fish Breathe