I did something stupid. I bought a school of harlequins from Petsmart even though I saw that a few of the had bad fins. So far, in three days I have lost 3 of them. I want to get Melafix for them. In the future, I am definitely going to put invertebrates like snails and shrimp in the tank once it has time to establish. The tank was fish less cycled and I have yet to see any spikes in ammonia or nitrite and nitrate is 20ppm.