"Have used this product since 1984.. Goldfish, Koi, and even small Tetras have all Loved it, and lived long lives. (For the small fish like Goldfish fry, and Tetras, I flatten the pieces with a morter and pestal first). This product does not cloud nor contaminate the water of either a 40L Aquarium, a 250 Gal. watering troff, or even small ponds.. I have raised a variety of fish from fry to full lifespans solely on a diet of this product, and without any signs of any diet deffiencies whatsoever."