that's what i thought, if it safe for human consumption then it should be safe for fish but just don't know how much is too little.Ingredients are 1) water, 2) phosphoric acid 3) sodium benzoate. Phosphoric acid may raise your phosphates a little, sodium benzoate is toxic but deemed safe for human consumption in small amounts. I would say food coloring is safe to add. Do a water change afterwards to remove it