Well - it certainly possible to buy or build your own shark pond.
One option is to buy a preformed "poly" pond - which you can usually get thru your LFS Home/Garden Or Livestock store. Which is usually a round "fish safe" pond that's roughly 6-9' in diameter. Which is roughly 350-950 gallons - and make excellent small habitats for small benthic shark species such as bamboos, Epaulettes or coral catsharks. This is the cheapest option as one of these ponds -generally costs about 1/5 what a similar size glass aquarium would cost.
The 2nd option is build your own pond. Which has more benefits since you can customize the pond which ever way you want it. Be it with or without a viewing window. and make it what ever size you want. Naturally it may cost more than the preformed ponds - especially if your looking to add a viewing window.
The size & dimensions of the pond will ultimately dictate what kinds of sharks or rays you can keep. But for a well design pond - that roughly 400-1,000 gallons - your looking at the following species of sharks or rays.
Sharks
-Bamboos (Chiloscyllium) -ie Brown-banded (C. punctatum), White-spotted (C. plagiosum), or Gray (C. griseum)
-Epaulettes (Hemiscyllium) - ie Common Eppie (H. ocellatum)
-Horn Sharks (Heterodontus) - ie Californian Horn(H. francisci)
-Coral catsharks (Atelomycterus) - ie Coral (A. marmoratus), Marbled (A. macleayi)
Rays
- Round rays (Urobatis) - ie California stingray (U. halleri), & Cortez (U. maculatus)
Just a few species to consider.
