No its a 20 gallon, you don't need any larger for an adult. Besides, the majority of a 40 gallon tank's extra space over the 20 is in height which BPs do not need. It isn't very much longer or deeper at all. I put them side by side at the local chain store to see for myself before I decided on the 20L. For that setup I posted I spent about $180-$200 total for EVERYTHING but that is how you do it right for a 20L tank. If you have 2 it'd be much cheaper to just build a tub rack. I would never house them together as it can stress them out, make them compete for the "best" spot in the tank and EVERY experienced keeper I've ever talked to advises against it.