Paranox is a combination of TMP Sulfa, De-Los, Metronidazole, and Sodium. It can be used as a general quarantine preventive, but is designed to be used when fish begin to die for no reason. It is also good for angelfish and discus plague which are viral diseases, as it prevents the fish from getting a secondary infection. Parinox is excellent for treating viral disease or when a confident diagnosis cannot be made. If a correct diagnosis can be made, it is strongly recommended that you change your treatment regimen to a more narrow spectrum treatment.