I think I know what you are talking about we see them at ren and ren island all the time. Are they kinda clear, blend in with the sand and water? You can see them, usually the eyes and they swim in small schools. I'm not sure what they are, I am sure if you look at an Aruba Tropical fish card you could probably pick it out. Might be a silverside.
http://www.frankosmaps.com/grafixbin...fish_card2.jpg