Mine was in a large, fully stocked tank (and good luck catching most of the fish).I was very lucky not to have a breakout in a large, fully stocked tank. This was a nano with only 2 or 3 fish and I honestly don't know how it found its way in since I hadn't introduced any new fish for a while when the breakout occured. The only thing I could imagine is I just happened to be that 1 in a million who happened to introduce an invert and the parasites were in the bag water...terrible experience I'd prefer not to repeat.
NOTE: I don't pour all the bag water in my tank but some obviously could have made it in...

