I just purchased two oscars 3 days ago they are small still , I noticed some strange behavoir they seem to be skimming the top of the tank even though they have already been feed, they look like they are sipping water? they do this for long periods of time is this normal ?, would appriciate help I dont want any floaters I have become some what attached to them already, and yes I feed them regularly just afraid they are sufficating or something I have heard horror stories =( I am a first time fish owner