Actually it wouldn't be good to keep aCalifornia Stingray & and a Coral Catshark together - As they have different water temp preferences. Cali Stingrays do best when kept at water temps below 70F. While Coral Catsharks require water temps of at least 74F.
A better combination would be a Coral Catshark with a Cortez Stingray - similar water temperature compatibility.