How should I go about cleaning a tank after the loss of my six fish? A little background on the situation. I had a five gallon bucket that was used strictly for filling my 36 gallon aquarium. I recently rescued a dog that doesn't handle car rides so well. I went to visit some family that lives a few hours away from me, and to keep a long story short, the dog ended up vomiting in the bucket. Normally I keep the bucket under the fish tank, but when I came back I stuck it under my kitchen sink, I was planning on getting a new bucket for my fish. While I was at work, my girlfriend decided to rearrange our living room, my girlfriend rarely cleans the tank since its sort of my hobby, so I completely forgot to tell her about the bucket. In order to move the fish tank she emptied half of the water and refilled it using the bucket the dog vomited in. I came home from work to find all six of my fish dead Now I'm not really sure if I want to start over again, I had my fish for almost three years. But I was thinking about cycling the tank while I decide if I want to start over. What do I need to do to make sure the tank is safe for new fish? Should I just clean it with water? Is there some kind of cleaner that would be safe to use? Should I plan on purchasing new gravel? Do I need to get rid of my plants? Any help would be appreciated!