probably an easy one

i saw these while snorkeling. I cant find it in my book. waiting for the reef set to arrive. saw about 6 of these swimming together. they were about 2 to 2 1/2 feet long. all small fish vanished when they swam in. they were very very quick.

Bar Jacks

Look more like yellow jack to me...

I see a blue stripe on the top .. so i'd say Bar Jack ... but hard to tell from all these pics. Where were you when you took it ? Maybe that will help decide which was more likely. (but i say Bar Jack)

Bar Jack

Yellow Jack

Hot linked from FishBase

they were from cozumel. they were blue in color, as the picture shows. all the jack pictures i have looked at show the fish as a silver color. Plus the top stripe or bar is yellow

They look like yellow jacks to me.

Yellow jacks, though the blue coloration does make it a bit confusing. Yellow jacks also do tend to terrorize the small reef fish when they show up hungry.

Mark

PS -- that photo of yellow jacks from FishBase is awful -- it really isn't representative of what they normally look like.