I'm a big fan of listing the Pro's and Con's in a way that makes it easy to see what the reason for or against something would be. So....
Reasons to get fish.
2. Feed the bacteria cycle.
Reasons not to get the fish.
1. Some smaller fishes, such as Wrasses are notorious jumpers.
2. While the waste the excrete does feed the bacteria, it will also put a higher bio load in the tank for the bacteria to bring down. The inverts are much less demanding on the bio-load capabilites and would require signifigantly less bio filtration.
3. Expense verses the instability of smaller tanks. The expense of a 25.00 fish going into a tank that may or may not be able to handle the load can get very expensive not to mention frustrating if it has to be replaced frequently.
My suggestion....put some really cool inverts in the tank and enjoy!