artist

i was just wondering how big of an aquarium they will need? i got them at the petshop and didn't know they were going to get so big but i will get a bigger aquarium if i can i got 2 of them and they're about 2-3" i currently only have a 29 gallon tank also in the tank with them are 3 blue gouramis, which are about 1 1/2" right now, and a betta also is there any way to tell if the kissers are male or female? thanks