I just noticed a pretty stagnant area under a piece of slate in my tank. There was a lot of old icky food under there that got stirred up. I'm worried! If my fish eat that food will they get sick? I'm going to do a water change first thing in the morning. I cranked up the pump to pump the max gallons per hour after that stuff got stirred up. I was looking for a missing fish, sadly I found him dead I would have done a water change right away but its now midnight. I'm soo worried about my other fish now. 7 cories and 4 guppies also a few fry. Could that nasty spot be making the fish ill? Please someone set my mind at ease