The shark will get along with your fish. Its just a question of, is the fish too big for the tank? I've read that many smaller types of sharks can fit into a 100 gallon for life, so I'm sure they would be OK in a 90. If you do get one try to get it small as possible and don't feed it all that much so that it doesn't get too big, too quick.
I've never kept a shark in my life so I couldn't tell you from my own personal experiences. But I have read that the differant bamboos will do OK in a 100 gallon(although when fully grown, they may need an even bigger tank 100-150 range.) I've heard of people keeping baby leopards and nurses in a 100, but I wouldn't do this unless you have a FOR SURE home for the fish once it gets too big for the tank.
Even if it was the only fish, no way could you keep a bamboo in a 100 or 125 for life. Read some of the other posts, you'll notice a consensus. A coral catshark maybe but a bamboo wouldn't last more than a couple of years.