Check out logic in action.

Question: Do animals and fish feel pain?

Answer: Yes

Reasoning: Because if animals and fish didn't feel pain, they would do stupid things and kill themselves. Birds would fly into fires and die. Rats would get bitten by snakes and not struggle to get away. Bass would grab a shad in it's mouth, and the shad wouldn't struggle because it didn't feel any pain. Of course fish feel pain. Pain is a survival tool for every animal alive on this earth. If they didn't feel pain, they wouldn't react to things that were about to kill them.

Catch the fish, handle it right, let it go. Feel confident that the fish will survive. Feel good about yourself. If the fish feels some pain, who cares?