If you're going to buy show size fish, I wouldn't recommend anything smaller than a 120 gallon (2high 2wide and 4long).This will allow you to put your hands in the tank with a lower probability of being pierced or bitten, and, the lion can turn himself around without hitting front/back glass.

If they're small specimens, they should be able to live in a tank considerably smaller (55-75) for up to several years.

If you go to small on the tank, you'll regret it later. I definitely have.

andrew