I've been using them both. A friend gave me a rescued former carnival prize comet to add to my new pond. He had been kept alone in a bowl for a few years. (She brought the poor thing to me in a gladware container.) Within a few days, the carnival fish began to sit on the bottom with clamped fins and various other symptoms that could be signs of bacterial or parasitic infections. My pond is new and had only recently cycled with 4 feeder goldies. I wasn't keen to start messing around with anti-biotics and anti-parasitics. The lady at the local pond shop recommended these supplements. I followed the directions and alternated doses evening and morning for the 10 days. The fish recovered. A week ago, I added another carnival fish and he's experiencing similar symptoms (assuming now that it's stress) and am in the middle of another 10 day course. Not sure if it's the supplements or the fish recovering on their own, but it sure hasn't hurt my plants, fish, frogs or water quality.