I have a tank that two fish have died in. I did not think the disease was contagious until I added the second fish in it a couple weeks later, only for it to have the same fate so now I am uneasy about adding another fish until it is properly disinfected. After the second fish died, I removed the water, not really cleaning the gravel. Then filled it back up, it has now been around three weeks with the same water and with no fish. Any help would be appreciated greatly. Also if there is a natural way without medication, that would be even better!
Thanks