I am VERY VERY new to the hobby. I have a 20 gallon tank. I have a sponge filter and recently bought a heater after the outbreak. I had 3 tiger barbs, 1 powder blue gourami, and 3 moonrise tetras. All get along, surprisingly, and I loved my set up. One day, without the heater, my house dropped to 69 degrees and my tank in turn got cold. That’s when I noticed Ich on one of my tiger barbs but had no idea it was Ich. It died that day.. it was sad. After doing research and finding out it was Ich I rushed to my pet store bought salt, a copper Ich medicine, and a heater. My two barbs are really the only ones in the tank that have it the worse. One of the lost its back fin completely and I don’t know how that happened. Please help me. Please be nice as I am again VERY new to the hobby. I want to succeed and this is really bringing me down.