Do sea fish breathe the same as fresh water fish?

Yes, both saltwater and freshwater fish breathe oxygen from water, but they have different ways of extracting oxygen from their surroundings.

Saltwater fish have gills that are specifically adapted to extract oxygen from the saltier water of the ocean. Their gills are larger and have a higher density of capillaries, which allows them to absorb more oxygen from the water. They also have a special organ called the chloride cell, which helps to regulate the salt balance in their bodies and maintain the correct osmotic pressure.

Freshwater fish have gills that are adapted to extract oxygen from the less saline water of lakes, rivers, and ponds. Their gills are smaller and have fewer capillaries, as the concentration of oxygen is lower in freshwater compared to saltwater. Freshwater fish also have a different type of chloride cell, which is responsible for regulating the salt balance in their bodies and maintaining the correct osmotic pressure.

Both saltwater and freshwater fish use their gills to actively pump water over their gills, which allows oxygen to be extracted from the water. The oxygen is then transported throughout their bodies by the bloodstream. The process of respiration is essentially the same for both saltwater and freshwater fish, although their adaptations may differ slightly.