One of the best parts about fishwatching is that no matter how many surveys you have under your belt, there's always a chance to see something unexpected. Recently I was diving on Davey Crocker Reef near Tavernier in the Florida Keys with four REEF surveyors. As often happens, we got separated, me with my photography and the others surveying. I spotted a brown fish about 8 inches long “drifting” in the water just under a ledge overhang. It sort of looked like a croaker to me, but not one that I recognized. I photographed it from a distance and continued to photograph while moving closer. The fish remained still, just looking at me. Finally, when I got about 6 feet away it retreated into the gloom under the ledge.
Back on the boat we were talking fish -- as usual. One of the others commented about a strange brown fish she had seen under a ledge. It turns out everyone had seen it and no one knew what it was. The entire group were members of REEF's Advanced Assessment Team (AAT, Expert Surveyors), so no one knowing is surprising. After downloading my photos, I researched the mystery fish. My hunch was correct; it was a Croaker, a rarely seen Blue Croaker, Bairdiella batabana. These were the first sightings of this species to go into the REEF database!
So how do you know if it's a Blue Croaker? The body coloration can be copperish to bluish brown. The only distinctive marking is a white crease on the gill cover.