The monterey bay aquarium had a baby great white in their million gallon tank. They released it back into the wild after a little because it wasn't nearly a big enough tank, lol. They've done this with a few babies that have gotten caught.
I would make a huge cardinal breeding facility and make a monopoly on selling them because I got all of my equipment for free. Lol.
Either breed endangered fish, or divide it in half, make a kelp forest biotope with horn sharks! and then on the other side put an arrowana, cardinals, ghost knife fish, aripimas, oscars, big cats...probably would go insane before I would get to finish from the sheer coolness. Then I would swim in it.