I run a home daycare and caught one of my young charges (3 years old) washing his grubby little hands in MY FISH TANK! His hands were reasonably clean before hand (or so I hope) and my tank is fishless, but I'm wondering now if he contaminated the tank. I was planning on buying new fish tommorow complete with Tetra safe start. Should I now maybe put off my plans? Do a water change? What do you guys think?