One of our albino catfish has been acting strangely from the time we brought it about three weeks ago, but now it is even worse. It swims upside down, does back flips, gets caught up in the weed and then nose dives into anything in it's way. At times it will lay on the bottom of the tank either on it's side or at weird angles, and looks dead, except that you can see the gills working really hard. The other fish in the tank (25 guppies and 3 other catfish) are doing just fine. The tank is 144 litres, pH nuetral and tank is cycled. Does anyone know what could be the problem, we wake every morning to find it alive and not floating on the surface of the water as expected.