I just started my tank 5 weeks ago and had my water tested and made sure it was ready for fish. I got a clown 3 days ago and he was dowing fine. I was cleaning the tank and filter and notice he was twitching. I don't know what's wrong so I tested my levels and everything is perfect. I haven't seen him eat except for he nipped once. I put the food in at night and turn the lights off. When I wake up all the food is gone but it could have just gone in the filter or skimmer. I don't know what's wrong with him please help.