This is a Spiny Dogfish, also called mud shark (to scare children).  While we were
tied up here it's all the fisherman on board pulled up.  You can't even use them for
bait - the fish smells badly of amonia.

This was at Kahalu'u Beach - the fish seem very tame.  This is a smaller fish and
didn't school.

The fish with the vertical bars are called Convict Tang's (Acanthurus triostegus). The larger black fish are probably Ring Tail Surgeonfish (Acanthurus blochii) but the photo is quite low quality.

The bright fish in the foreground is cool, but as you look into the scene you see another, and then another fish.
It must not be that hard to camoflage in this environment, so the decision to use something like
bright white and yellow, must have some biological advantage.

Coming, going, you tell me - these fish (like me) were being dragged in the current and (unlike me) stopping
on each ebb to chew one whatever was on the rocks.

These fish just hang out on the bottom in the flow.  From a distance, they look like some sort of grass just dragging in the current, but they are live.

These fish grow to be 60 cm long - this is just a little guy!  We put this one back.