Ricey - Not sure where you get your information from, and I highly doubt you have any experience with any of the two species listed above. So please get your facts straight before going ahead and posting information which is false.
Stingray12 - Most aquarium friendly sharks require tanks from at least 350 - 3,000 gallons. However you have picked a specimen which will be a little easier on your wallet. The Coral Cat Shark is one of the smallest sharks available in the aquarium trade, however it still needs a tank of atleast 250 gallons to live ethically for life. Now keep in mind, length and width is more important than height. So just because the tank is 250 gallons make sure the dimensions are right. I would aim for atleast 30" width, and atleast 6' length. Ensure you purchase a very large protien skimmer, rated atleast 2-3x larger than your system. So for a 250gallon system, get a protien skimmer rated for 500-700 gallons. I would preferable run a large sump, refugium, and run a closed loop rather than power heads. Make sure you get alot of flow and circulation. As mentioned by Ricey you will need a very fine soft substrate, I would go with Aragonite, and keep the LR to a minimal to ensure you give ample swimming space.
As for the Blue Spotted Singray, I wont get into scientific names, however there are two specimens which share the common "Blue Spotted" name. One is better than the other for the home aquarium however I do not recommend either as they do not have a good history of saying alive and healthy in the home aquarium and require a large, mature system which will be hard to offer. As a substitute I would recommend the Cortez Ray, still a great looking ray, and its one of the smaller rays available in the home aquria.
Again, both the Coral Cat Shark and the Cortez Ray are compatible however I would go with a system around 250-300 gallons. Again atleast 30" width with minimal live rock, and atleast 6' in length. If you proceed with this be very careful with the tank mates you chose. Below is a list of good tankmates and BAD tankmates:
Good Tank Mates:
Groupers
Eels
Tangs
Porkfish
Lookdowns
Clownfish
Squirel Fish
Bad Tank Mates:
Angels
Puffers
Butterflies
Triggers
If you need anymore information, please PM me privately. Or vist Shark & Ray Central for more information, we offer both a captive care sheet for both specimens you have showed interest in.
Good luck.
Thanks, Brenden