I have a 40 gal breeder with a marineland penguin 350 hang on. The stock list is as follows I have 6 mextico blue about a 1in or 2 , one three in. ebjd(just having in the till he gets a little bigger then i am moving him). I have 2 rainbows cichlid in there ones about 5 and the others about 4 inches. My question is am i overstocked . Also can i add some livebearers if at all possible.