So I have to tanks a 20 gallon and a 90 gallon. I work away from home so the wife takes care of the fish. We have been using "omega one-tropicalflakes" since we first got fish. As the small container we have was about empty she bought a big jar of it and gave it to the fist in the 20 gallon. Well within 5 mins half the fish in the tank had died all where in shock and all died within an hour!!!. Anyone ever hear of anything like this b4? The water is perfect and a water change was done right about 24hours ago now.