welcome,
i'd say about 35 lbs
and what do you want from the tank? there are so many species out there, and a 25 does ahve a few possibilities
firefish, chromis, clowns, most gobies, or maybe some smaller wrasses
I have a 35g hex with 40lbs of l/r and 30lbs of l/s. I have two percula clowns right now and a mandarin goby. I'm keeping my eye on the mandarin because everyone says they are picky eaters and will starve to death without pods. The clowns are great, but there are lot of other fishes out there that will work, just make sure they don't get too big.