API Fin & Body Cure API Fin & Body Cure is a powder medication that treats bacterial infections in freshwater fish, both internal and external — including fin and tail rot, bacterial body slime, and the open sores and ulcers of more advanced infections. It's the API "Cure" line's bacterial-disease treatment, supplied in convenient pre-measured packets. Good to Know: Fin rot and body sores are among the most common bacterial problems, and they usually trace back to poor water quality or stress — so test your water and correct conditions alongside treating. This is a more serious treatment than gentle herbal remedies, appropriate when an infection is clearly bacterial and advancing. A Caution for Inverts: As with most fish medications, keep it away from shrimp and snails, and treat in a quarantine tank where possible. Remove chemical filtration (carbon) while treating, since it will absorb the medication. Dosing Guidelines: Dose per the label using the pre-measured packets for your tank volume, completing the full course. Do a water change between doses as directed, and finish the course even if the fish looks better.