I wouldn't I'd let him go. A fish that big shouldn't be taken out of water. It's bone structure isn't designed to withstand the pull body weight against gravity.
Yeah, unless I was trying to get it weighed for a new world record, I'd let it loose without taking it out of the water. Trying to figure out how one would arrange a live weigh of a catfish that big ...
"Decency is not news; it is buried in the obituaries --but it is a force stronger than crime" ~ Robert A. Heinlein, 1952
I can't give legal advice yet, but this site may have some of the answers you need: https://texaslawhelp.org/