Rainbowfish are such cool fish, but they do come from waters with their own specific mix of minerals and trace elements. This formula is made to help replace those little elements that can get used up over time or pulled out by things like carbon and chemical filtration.
It is designed for rainbowfish, and other fish from Australia and New Guinea. The added trace and minor elements support normal metabolic and neurological functions while also helping provide what fish use to maintain their natural coloration.
The best part is that it does all of that without significantly raising your GH or KH, so you are not completely changing your water parameters just by adding it!