my soon to be roomate wants to put a blue gill hes had in his 20g in an empty 29g i have in storage.... i need to know more info about them as in is it a general name for multiple types of fish, how big can they get, is a 29g big enough, what kind of food can we feed them, etc. i dont want to keep it if we cant keep it in a healthy and comfertable environment. any info will be appreciated thanks