I have a 20 gallon planted tank right now with 4 gold barbs, 3 glowlight tetras, 2 silvertip tetras, 2 panda cories, 1 peppered cory and a 3 in pleco (will be moved to a 55 gallon once he hits the 4 inch or so mark) I have the chance to get a pair of australian rainbows from a friend for free.....If i add those two do you tihnk that would be to much for the tank?