Those fish have been caught before. The behavior tells the story. That is one of my biggest pet peeves with catch and release fishing, because the fish learn not to be caught and it makes it that much harder for people to catch fish for dinner. Fish are smart. Crazy smart. People say "it's just a fish", but its not. I have had pet fish that would get all excited and start jumping and splashing when I would get home because they wanted a scratch and a treat, just like a dog. We had a big red bellied paku that we named burger. He ate all his tank mates, including the sharks. Look 'em up. He was like a puppy dog and loved getting petted.