i used to have that same tank until i knew how much they are not liking it. (i kinda took the hint when they kicked the bucket in the 1st 2 weeks) :( so i returned it & got my money back.
it is only about 1.5 liters and thats not near big enough for even one fish.
and the ammoina build up i expeiriance is horific. so i highly sugest you get you get a larger tank so your fish are happy and your not constantly changing water.