Finally, substrates designed specifically for the advanced cichlid enthusiast. CaribSea's African Cichlid Mix is derived from a rare dark colored calcium carbonate which will not only maintain an exceptionally high pH and carbonate hardness but also discourage cichlids from “fading” into the background. African Cichlid Mix is a must for healthy, vibrant African Cichlids (great for other hard-water freshwater fish too!).