I need bullfrog help!!!!!!?

Well today I went to a public pond and cought this huge american bullfrog. And well he's the first frog I cought and well he's just so cool and I want to keep him sooooooo bad. My mom disaproves and my dad is very questionable about it... I curently have him in a 20 gallon long and he has proper filtration and lighting. But what I need to know is how to persuade my parents to let me keep him and how to take proper care of him. PLEASE HELP!!!!!!