I am not quite sure what's going on but hopefully someone here can help. I just performed a 30 gallon water change on my 100 gallon tank and afterward I put my hand in the tank to grab some Chateo and got a very harsh stinging sensation from the tank on my hand. I am almost confident it was not stinging me prior to me performing the water change. I turned off all the electronics and still felt it so it is not something electrical. In the middle of the water change I caught and removed my foxface from the tank, could it have released its venom? To add to the confusion, I've had 2 other people thus far put their finger in the tank and they do not feel anything at all. I do somewhat bite my nails though so my fingers may just be more tender. I felt my water in my mixing container and felt nothing, so it's just in the tank. Any idea what's going on here? Anything I should do?