I was fishing several nights ago and flipped a nice 25 inch slot redfish into the box. Didn't look that close at it. Just as I finished filleting it at home I noticed an algae coated tag laying along its dorsal fin. This tag appears old as algae growth was almost an inch long on the tag. The tag is red and about 4 inches long. I can't see any writing on it but the algae covers most of it and I didn't want to scrape it off and damage any writing on it. What is it and who tagged it? Suggestions?