OK, when you mix that caustic potash (AKA Potassium Hydroxide) with vegetable fats, a chemical reaction called saponification occurs and you get surfactants. Th

OK, when you mix that caustic potash (AKA Potassium Hydroxide) with vegetable fats, a chemical reaction called saponification occurs and you get surfactants. This is exactly how they made soap in the olden days. Fish are extremely sensitive to surfactants, as their skin is covered with a thin protective fatty membrane that gets dissolved. If you're still not convinced: go buy a goldfish, put a drop of this stuff in his bowl, and watch him die.