I want to upgrade to bigger tank

I have a 30 gallon tank with 1 rainbow shark, 2 albino rainbow sharks, 2 albino catfish, 6 black mollies, 2 snails. I want to get a bigger tank. What size should I get if I want to get a few more fish?

 

You're looking at at least a 55 gallon for one shark & rainbow sharks should be kept singly as they're aggressive as they mature towards their own species & other sharks.
What species are the albino catfish?

 

I agree with Coradee. What type of fish do you want to get?

 

You're looking at at least a 55 gallon for one shark & rainbow sharks should be kept singly as they're aggressive as they mature towards their own species & other sharks.
What species are the albino catfish?

Are rainbow sharks any different than red tail sharks in their personality? If not, then he will need something bigger than a 55 gallon with how aggressive they will be. Mine acts cramped in a 55 gallon.

 

Rainbow sharks are less aggressive than red tails. Mine is quite peaceful in his 55g.