Hi there - my tank has settled for the last few months with no problems - my 5 sparkling gourami and 9 cardinal tetras are getting on well, feeding and generally swimming about, the tank is a 54l litre number, with heater and filtration and a pH of 6-7, I know accoridng to inch/gallon rules that I'm fully stocked BUT my cardinals are tiny and I reallllly would like something else. Not sure what though, are there any fishes that can be kept in pairs that I could add? How about pgymy corys? Look forward to some suggestions - I just want to see if anyone can suggest one or two fish that are about 4cm long and colourful?...