Focus is an antibacterial polymer for internal infections of fish. It may be used alone or mixed with other medications to make them palatable to fish and greatly reduce the loss of medications to the water through diffusion. It can deliver any medication internally by binding the medication to its polymer structure. The advantage is that the fish can be medicated without contaminating the entire aquarium with medication. Fish find Focus appetizing and it may be fed to fish directly or mixed with frozen foods. Focus contains nitrofurantoin for internal bacterial infections. Marine and freshwater use. 5 gram container.