Oral lesions (mouth sores) make it painful to eat and talk. Two of the most common recurrent oral lesions are fever blisters (also known as cold sores) and canker sores. Though similar, fever blisters and canker sores have important differences.
You could do a school of White Cloud minnows, they require cooler water, so you wouldn't need a heater. I think if you check the profiles, the ideal temp should be no lower than 67 degrees. Not positive.or example: my goldfish tank is fine in the summer, but my house gets so cold in the winter that I need to have a heater to keep it above 70F. Fish need a constant temperature which is one of the reasons we use heaters.
According to Kaz, Inc. (the manufacturer of the PUR brand) and NSF, the standard replacement filter (Part# CRF-950Z) for the PUR family of Brita pitcher style water filters is certified by NSF to reduce 6 contaminants to safe levels.