They are rare and usually more on the expensive side. However I think for your tank with the Aro a way better option than the TSN.
They are more laid back, don't grow as fast and large and overall less aggressive, for a pred cat. But they also need better water quality to fully shine. You can see how well he likes the water at the length of the filament, if noone keeps biting it off.
An Awesome pick up. And yes, the are wild, since all Brachyplatystoma need to migrate in order to spawn.
They like clean warm water, a decent bit of a current and some covered placed to rest, like a large lifted plate in the Corner or big piece of wood, will be greatly appreciated.
They can turn yellowish as they age due to the fat, same as Wels catfish, but a healthy lean diet will prevent that.
Your animal looks very great, I am looking forward for updates.
