I have four small p's in a 55g. Three are about 2 inch and one is about 1.25 inch. I have had them for about three weeks. Ever since i've had them, I noticed the small p is always and I mean always opening and closing his mouth and flexing his gills. The other three open their mouths occasionally, but nothing like this. I t seems like he is haveing trouble breathing. He eats just fine but I can tell he is not growing nearly as fast as the the others. Any feedback would be appreciated. I have two penguin 330's in their. I don't know what his damn problem is.