There are many views of this product out there - ranging from "great product, saved my betta" to "killed my betta!" Here's my two cents: 1) This product isn't a miracle solution. It's a watered-down version of Melafix, which is widely recommended as a "fish first aid" product. It's meant to help support bettas recovering from fin rot or fin-nipping. 2) It's an antiseptic -- NOT an antibiotic. The active ingredient is a natural product; diluted Tea Tree Oil. It helps to keep cuts clean and free of disease-causing pathogens. It will not cure fungus, fin rot, or stop fin-biting, but it may assist in keeping cuts/scrapes from becoming infected. 3) It should not be mixed with any other medications (unless you know how those medications interact). 4) It should not be overdosed. 5) It does tend to create a clear, thin oily, "filmy" layer on the top of the water, I noticed. This doesn't seem to negatively affect anything. 6) This product does not appear to impact pH, harm the bio-filter, or harm aquatic plants. Many injured bettas seem to recover fine on their own, given clean water, so many view this product as unnecessary. However, I feel better having a bottle on hand just in case to prevent infection. I use this product whenever I bring home a new betta, or when transferring a betta to another tank, and once when I had a betta who tail-bit. I wouldn't do a full recommended duration unless I was supporting a very injured recovering betta. Some have noted this product as "dangerous" -- I believe it's only dangerous if used improperly. Many who have used BettaFix and blamed the death of their fish on the medication used Bettafix in conjunction with other meds (not recommended), overdosed (not recommended), or the fish was too ill to have survived any treatment. I have not seen any scientific study or evidence backing up claims that it "kills bettas" or "damages their labyrinth organ". Users should not forget this is a medication and to use the medication with care; just because it's "natural" does not mean it's "safe at any dose".