8 or 9 fishes is too much for that size tank. Unless they are all 1"-2" fish the bioload would be too much. I have a 55g and I will max out at 4-5 fish. I don't know anything about reef tanks but with the bioload you are considering I think it would be very dangerous for your corals. I've seen plenty of books that give unreliable information. Many books say that the minimum tank size for a Volatin Lionfish is a 55g, that's great when they are 2" long but the **** things get up to 24" full grown! It's hard to restrain yourself I know but it is better to be cautious with saltwater. Most of the people on these forums give good advice and have alot of experience. Kudos to you for researching both books and these forums before jumping into things! Oh yeah, be wary of your lfs advice! Unfortunately many lfs are just interested in selling fish and don't care what happens after that. If you read through the other posts on here you will see some pretty crazy advice from lfs's. I would consider 8-9 saltwater fish in a 50g bad advice.