I would also consider investing in a quarantine tank. A 10 gallon QT tank a couple pieces of PVC, a heater and a sponge filter along with a 30 day quarantine on all fish will help prevent diseases from getting into your tank and potentially wiping out hundreds of dollars in fish. This will allow you to treat anything that they come in with and it helps with impulse control (a problem I have) because you can't add a new fish to the QT until the last fish is out, forces you to move slowly and reduces frustration caused by common fish diseases.