A 48 x 12 x 20 is only 49.87 US Gallons,even less taking into account the glass wall thickness..A standard 55 here is 48 X 15 x 18 which is actually 56.1 US gallons before allowing for wall thickness.This is why we all should probably go on footprint and not Gallons.In a standard 55 gal 15' wide I wouldn't hasitate for 1 oscar.I have seen 2 O's 13'+ in a 55 gal (48 x 15 x 18) before and both fish were as healthy as any I have seen.IMO tank size only makes up for half the equasion.Filtration and the keepers house cleaning routine makes up the rest.Renteria;991360; said:nova your wrong about the foot print of a 55g. it is 48 X 12 X 20
that is not good for one oscar seeing as how a lot of oscars get 13in+.
people cannot put 3 oscars in a 60g. i guess its "posible" but its also possible to cram a 14in. midas in a 10g.