This afternoon I was checking in on my ADF and I noticed it appeared he was having difficulty swimming. His legs appeared to be hyper extended and bent in the wrong direction. He struggled for a couple of seconds and then was able to swim normally. I'm not sure what is causing this. So far I have removed him from the tank and placed him in a covered bowl with some aquarium salt in it. I fed him blood worms and it looks as though he is eating. Any ideas? should I be worried?