I tell my clients to put it in a plastic bag that is plenty big. Wrap the bag around the fish to get the air out then put that bag and fish inside a 2nd bag and do the same. Write your license info, date, location,etc on a card and put it with the fish. If you are hand delivering the fish after it is frozen, you'll be good to go--frozen or fresh. If you are going to have to ship it to a taxidermist, you need to wrap it in an insulator like newspaper. Don't let newsprint touch the skin of the fish! It will dry it out faster and possibly cause scale loss on crappie or redears PLUS you run the risk of the print ink getting on the skin. I tell my clients to not wrap them in towels either. Plastic is all that should touch the fish skin to give your taxidermist the best specimen available so he/she can give you the best mount of your trophy. Good luck.