Can Kisame breathe under water? He's still a shark. He has lungs but those things on his face are branchiae, right?
Kisame having gills on parts of his body means he is likely to be able to
He has small, round, white eyes, 3 sets of curved facial markings under his eyes, gills on his shoulders
However I don't believe Kisame was ever shown being able to inherently breathe underwater (somebody correct me if I am wrong), a majority of fans are speculating that he is able to due this factor and his overall shark-like appearance.
However, later on in the Shippuden series, Kisame is shown being able to breathe underwater when fusing himself with his sword
When fused with Samehada, he gains the ability to breathe underwater using gills which form on his neck
in the anime when he steals back chakra from Bee after exiting Samehada, its shown that bubbles escape the gills on his shoulders, so they might be functional.