big dif, run your hand across your Oscar once and watch him shed his whole slime coat. not going to argue this, if any thing you do can compromise a fishes immune system then there is no good reason to do it.
I do agree, although I am a huge fisherman and handle fish all the time! I highly doubt that handlin fish even for a few minutes like I often have to does much harm to them. If it did then why would native keepers occasionally catch their fish with rod and reel and hold them while they take out the hook? Just my opinion, but I do agree to handle fish as little as you can (although cats probably don't matter much since they don't have scales).