All fishes exchanges dissolved gases with the water using gills, and have paired fins. The Cartilaginous fishes have skeletons made of cartilage. They are the the sharks and rays. The are a lateral line, that sense vibrations in the water, and they lack an active system for pumping water across their gills. The bony fishes have skeleton made of bone.
Bony fishes have a gas filled swim bladder that they use to control bouyancy.
Typically terrestrial as adults with reproduction occuring in freshwater. Amphibians were thee earliest tetrapods. Skin is covered with scales composed of protein called keratin. There is no larval stage. They have amniotic eggs.