Aquarium Products' Gel-Tek Penicillin is a broad spectrum bacteriostatic antibiotic that exerts anti-bacteria action on susceptible organisms. It is effect against a number of gram-positive and gram-negative bacteria associated with fish diseases. Use for fin rot, cloudy or bulging eyes, mouth sores, bacterial infections, and septicemia. Safe for plants, reef tanks, and biological filters. Use 5 drops per fish twice a day. Repeat for 3 days. Bottle contains 2 fluid ounces.