Not Reef Tank Suitable
Not Suitable for Fish-Only Tank
Sharks and rays do not fall into the category of 'Bony Fishes,' which makes up the majority of this Fish Library. They belong to the Class Chondrichthyes, which includes nonbony fishes. Sharks and rays both fall into the Subclass Elasmobranchii, which includes jawed fishes with cartilaginous skeletons, multiple gill slits, skin covered with tiny tooth-like scales, and rows of regenerating teeth.
The classification of 'rays' is currently undergoing some changes, with the Superorder Batoidea possibly consisting of only the Order Rajiformes. Some propose as many as six orders. For now, I'll stay with what's below.
These rays mostly require a large, well-filtered system, with a fine grain sandbed, and few environmental obstructions even for the smallest members. They bury themselves in the substrate to conceal themselves from predators. Most succumb to poor husbandry skills. They cannot be treated with heavy metal solutions such as copper. Fresh seafood, such as shrimp, fish flesh, crab, scallops and/or bristle worms are welcome.
For much more in-depth information on these creatures I suggest reading Aquarium Sharks & Rays, An Essential Guide to Their Selection, Keeping, and Natural History by Scott Michael, ISBN #1-890087-57-2.