You've gotten a lot of great suggestions already. I'd also choose a yellow tang LONG before ever considering a hippo, myself. I just posted in another forum that I have a 120, and plan on filling it with LOTS of small fish (all the anthias, wrasses, gobies, etc. mentioned above) and a couple larger show fish, like a sailfin tang and a copperband butterfly. The small fish are really what make the reef "live." The other thing I mentioned was to consider selecting fish who have function, as well. The six line wrasse, as mentioned, for pest control. A tang and/or rabbitfish for algae grazing. Gobies for sand sifting... and so on. Then you get beauty AND function!