Yeah - Scott Michael's figure a extremely conservative.
But what most people don't realize is that in "Aquariums Sharks & Rays" when he states that a 180 gallon is the minimum for Brown Banded Bamboo - his basically talking about a juvenile, not an adult. Based on his own figures - which are too conservative in the width department - and Adult Brown Banded Bamboo would need at least a 300 gallon tank.
More Ethical estimations would suggest about 450 gallons for a Brown-banded. And using the same ethical estimations for a Coral catshark - you would get about 250 gallons.
Basically the minimum Ethical figures are most benthic sharks in Home Aquaria is as follows - Tank Width = 1.25 x the shark's maximum length, and Tank Length = 2.5 x shark's maximum Length, and tank depth at least 2 ft.
So for a Coral Catshark (Atelomycterus marmoratus) maximum length is about 28". So the tank must have a width of 35" , a length of 70, and depth of 24". Rounding to the nearest foot that's 72" long, x 36" wide x 24" high or 270 gallons.