I saw these several time while snorkeling off Cayman Brac, but they're not listed in my Caribbean fish guide. I'd appreciate any help.
--Pier Carlo Talenti
You saw bar jacks. They can be IDed by the black stripe running from the top of the fish's back and extending to the lower part of the tail. They aren't the largest of the jack family and are pretty common around coral reefs.
That neon blue stripe against the black one can be quite stunning. Absolutely beautiful silver fish.
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