Hello everyone! I looked in my tank today and noticed my male’s tail was way shorter than normal! I have removed all decorations and unplugged the filter. I added real plants and want to turn up the temperature. He is currently in a 5 gal tank with a tetra heater. The box said the heater would keep the water around 78 degrees f. However, my tank thermometer says its only 70….consistently…. has anyone experienced this? What heater should I get to replace this so his tail can grow back?