What 3 Functions Do Gills Perform?

The gills have three functions. When water is passed over the gills, oxygen is absorbed and carbon dioxide and ammonium is exhaled. 75% of the ammonia excreted by the fish is through the gills. The gills also help the fish osmoregulate, (equalize body pressures). The two gills are located on the head of the fish, just behind the eyes. They are covered by a boney flap known as the operculum. Each gill consists of a bone arch with filaments extending at right angles to the arch. Lamellae are the tiny branches on the filaments. Healthy gills are bright red and do not stick together. Signs of trouble with the gills are listlessness, flashing, and rubbing. Examination of a damaged gill will show excess mucous along with hyperplasia and a pale color.
Swim Bladder or Air Sac