Originally Posted by I<3Fish
Just a couple points... and don't take this like a flame because I, like a lot of others here, share your interest in sharks and rays. First, a 180 is definitely not huge. Getting a shark or ray will show you how small such a tank can look. Second, one of the most difficult parts, IMO, of having sharks and rays is selecting appropriate tankmates. The options are severely limited. When keeping these guys, "impulse buying" will lead to huge failures in your tank. If you decide to get one or both, people on here are always available for help. Getting sharks and rays will severely limit your total fish capacity simply because they are large waste producers and get so large themselves. Finally, unless you end up with the smallest species of shark, coral catshark or grey bamboo, you will need to upgrade eventually for the shark to live its full lifespan. Even with a coral cat or grey bamboo, most people will suggest that a full grown one needs a larger tank than a 180.
All that being said, if you can accept all these principles and not try to break the rules or outsmart nature, like so many attempt, then these guys are awesome to keep. But for right now, you are just starting and have had some failures... get the 180 going, learn how to keep the tank stable and keep your fish alive. When the time is right, I'll be happy to offer as much advice as you need.