Some people say that you can put a corycat in a 2galllon tank and some people say you can't. I have a betta in my 2 gallon so could i put a corycat w/ my betta?? 
Harlock said:Short Answer: No.
Long Answer: Cory cats are extremely active fish and a 2 gallon tank would be a cruel existence without being able to stretch their fins and behave like a normal cory. Cory cats are schooling fish and need others of their kind to be comfortable and live normal lives. A 2 gallon tank prohibits adding enough cories for a school and sentences them to an abnormally cruel and lonely existence. Cory cats need stable and clean water and overcrowding a 2 gallon tank is cruel and likely sentencing them to an early death. Cory cats are simply not suited for a two gallon tank, even without a betta in it. Please don't try it.