HomeWhy do fish and other living things have different roles in the aquarium?What are the functions performed by fish? Why do fish breathe? How do fish breathe?

How do fish breathe?
      Fish use a specialized organ called gills in order to breathe the oxygen dissolved in water. The mouth and throat of a fish force water over the gills. Gills have a lot of blood vessels. The water has a higher concentration of oxygen than the blood. Therefore the dissolved oxygen from the water moves through the thin walls of the blood vessels and enters the blood. Once the blood is fully oxygenized, it is pumped back into the body and used by the fish for energy and for all metabolic processes in the body.

What is the structure of gills?