Planarian is a parasite and harmful to fishes, shrimps and snails in aquarium. Planarian will quickly propagate, prey on fish and shrimp, and is parasitic. Direction: Apply 1 tab to 50L, please refer to following table. The efficacy will be affected by the water conditions(Temp/GH). The daily dose can conduct 3days most depend on the severity of planarian. If planarian remains, please change ½ water then repeat above process.