My response is to listen to both of your other responses. I work at PetSmart in the fish department and we usually recommend that you have your tank running for 2-3 days before you put fish in the tank. Bala Sharks get 13 inches in length and they will out grow that size tank. I would recommend using stress zyme and stress coat in the tank, try some zebra danios if you want schooling fish or some bigger tetra's like black skirt tetra's. If you have any other questions I will try to help. Talk to you soon.