I agree with the others, rays need delicate care, a LOT of space, cost a lot... Get yourself a hillstream loach... They are also poisonus. It is obvius you didn't even use the search button, or google!! Giving any info to someone like that is pure vaste of time... Please research fish you even think about ownung someday before making a topic like: Oh I want to have one of the most expensive, most hard to keep fish, I am wondering if I am "mature enough", I have a 30 gal tank...
Sorry for the rough words, but that's how it is...