Take an old clean t-shirt and tie up the arm and head holes, place it in the water and grab the edges with your hands and then use it like a fishing net. It would help if you drain as much water as you can so theres less room for the fish to escape. And if you have decent size catfish, ie a pleco, rap the t-shirt around your hand then slowly grab it frim above firmly, it gives you better grip and some catfish have sharp spines.
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