Gills are used for respiration, not digestion.

The swim bladder is filled with gas, which helps the fish to control its buoyancy and maintain its position in the water.

Pelvic fins are not found in all fish species.

The gills are the largest organ in a fish, and they are responsible for respiration.

The lateral line system is a sensory system that helps the fish to detect movement in the water.

Ganoid scales are not found in modern fish species.

The operculum protects the gills, helps the fish breathe, and controls the flow of water over the gills.

Edentulous jaws are not found in fish.

The spiracle is a small opening that allows water to flow over the gills when the fish is out of water.

Molars are not found in fish.

The pyloric caeca are small, finger-like projections that extend from the stomach and help to absorb nutrients from food.

Gill arches are not blood vessels.

The heart pumps blood throughout the body, regulates the fish's body temperature, and helps the fish breathe.

Agnathan kidneys are not found in fish.

The swim bladder is filled with gas, which helps the fish to control its buoyancy and maintain its position in the water.