i have 9 rosy red minnows in a 15 gallon tank and every now and then i see them at the top of the water, almost look like theyre gasping for air. what are they doing and why??
1) You'll need to do a water change to get those levels down, that'll cause your fish no end of stress and damage. 2) Airation, how you get oxygen into the water Either with surface aggitation via the filter outlet, an airstone or a combo of both.