Thomas Labs Fish Pen (Penicillin) exerts a bactericidal action on gram-positive and some gram-negative bacteria.
Dosage & Administration Add one tablet (250 mg) into aquarium for each 10 gallons of water to be treated. Repeat in 24 hours. It is suggested that a partial water change be made between treatments. While duration of treatment depends on type and severity of the infection, it is recommended that extended baths in the medication continue for a minimum of 5 days & for not more than 10 days. Discontinue treatment with this medication if no improvement is noted within 5 days.
Keep out of reach of children. For aquarium use only. Intended for ornamental fish and/or ornamental organisms, and not intended for use with fish for human consumption. For those allergic to penicillin, do not put hand in tank for three days after treatment.Store at controlled room temperature of 59??-86??F. (15??-30??C).