I bet your BIL & nephew know what it is & have eaten it. You haven't lived till you've eaten snook!
Here are some links. Despite what Wiki says; I have never, ever, never seen foreign caught snook for sale in the US nor have I ever heard of it. it's illegal to catch it here & sell it so you can only get it by catching it yourself or by having a friend or relative who loves you enough to share their catch with you.
http://en.wikipedia.org/wiki/C...
http://myfwc.com/fishing/saltw...