There seems to be some debate as to the bare minimum based on published books.
While "Aquarium Sharks & Rays" states the bare minimum for benthic species of sharks -such as Bamboos, Eppies, Horns, Coral catsharks, wobbegongs & Nurse sharks - is the tank/pond needs to have a length at least 2-2.5 times the shark's maximum length. And a width that at least 75% of the shark's maximum length. So a Coral Catshark(max of 27") - would need a tank that's at least 60" long x 20" wide. Which suggests a tank of only 110-125 gallons.
On the other hand "The Conscientious Marine Aquarist" lists the minimum dimensions for any benthic shark - as a length of 4 times the shark's max. length. And a tank width that is at least 2 times the shark's max. length. So a Coral Catshark - would need a tank at least 9 ft long x 4.5 ft wide. Which suggests a tank of 600 gallons or more.
The average of these two would be approximately a tank that is 7 ft long x 3 ft wide, and roughly 315 gallons. Which personally I would consider much closer to the absolute bare minimum for a single adult coral catshark.
