I also made a lionfish and a seahorse puppet for the fish film. Just basic wire armature for the seahorse.
Hot melt glue for the bones. Cushion foam to build up muscles.
This the is lionfish armature. I drew the fish to scale. Cut a MDF block for the body, drilled some holes for wires. Hot melt glued the wires in place. And glued in a square brass K/S tube for the flying rig.
Cover the whole thing with dabbed on black and white latex.
Go ahead, make a mess, have some fun.