Ok, I have a 30 gallon tank. No protein skimmer or any live coral.
Filter is a hang on the back type. I have one fish in it: a clown. I has
been doing pretty good for about five or six months.

Anyway, I'm thinking about putting another clown fish in the tank, so my
first clown can have company. Is this a big no no or what? Or will two
clowns be okay in the same 30 gallon tank?

Thanks!