I don't think flukes would cause the fish to go from perfectly fine to looking like that overnight.
Look at the lines on the side - there are two patches on the fish where the lines are interrupted (but fish does not have junk on it here). This really seems like physical damage to me. Combination of missing and raised scales and slimy patches with some other debris mixed in.
Look at the lines on the side - there are two patches on the fish where the lines are interrupted (but fish does not have junk on it here). This really seems like physical damage to me. Combination of missing and raised scales and slimy patches with some other debris mixed in.