hope to see pics soon, normaly an RBP needs 80 liter swim water. you have 2 of them so 160 liter.
how manny gallon is that ? i believe it is times 3 so you have a 60G so roufly 180 litr. so no worry's they will do fine.
make sure you have good filtration, 3 times the size of your tank.
do a weekly water change of 30% feed the little friends ones in two days.
also give them alot of variety in there dieet.
if you give them lifefood NO GOLDFISH!! that wil effect there growing procces.
good luck and keep us posted.
sorry fore my bad english, but i'm sure you know what i mean lol