The neon tetra I asked about in this thread is no longer among the swimming. He was the last surviving fish (both of his tank mates died within the past three months despite looking far healthier than him) so the tank now has no fish in it. I don’t think his tankmates caught whatever it was that made his tail fall off from him, because as I said they didn’t end up looking sick before dying, but I don’t want to take any chances that what he had could have been contagious and be passed along to the next fish I own.
Besides changing the water, what should I do to prepare the tank for new fish? And what’s the best way to ensure that the tank and its contents don’t harbor any germs that would kill the new fish? The tank (5 gallon acrylic) currently contains: half a dozen live plants, a ceramic “house”, a heater, a filter and glass “rocks”. And is there a way to clean the tank adequately without destroying the biofilter?