Especially if new to fish keeping DO YOUR RESEARCH before using this product. The dosage instructions are incredibly misleading both on the bottle, website and from PAH staff. Do NOT dose based on the volume of your tank as instructed. Calculate the dosage based on the ACTUAL volume of water in your tank, taking into account the amount of water displaced by substrate, driftwood, rocks, plants etc. You can find the ways to calculate this on various fish keeping forums etc. After buying 6 new WCM minnows from PAH for my sons first tank I noticed one of them had fin rot and the begining of a fungal infection. Contacted the store and they gave us this treatment. The active ingredient does indeed have good antibacterial and anti fungal properties but is also used as an anesthetic for fish (I think we all know how dangerous anesthetic can be) and dramatically reduced available oxygen in the water. I followed the manufacturers and PAH staff's guidance to the letter, including shaking for well over 30 secs, using the manufacturers website tool to calculate dosage and increasing oxygenation. Within minutes we had very slow, drunk looking fish. After a quick read on various forums and aquarium specialist websites it became apparent that by following the instructions I had inadvertently overdosed the tank and that this treatment is notorious for this due to the lack of proper information provided. Did an immediate 50% emergency water change and added the organic media back into the filter to clear the medication... they slowly perked back up but all we can do is wait and see at this point.