Penicillin for Fish (Fish Penicillin)
Quick answerPenicillin is the original beta-lactam antibiotic. It kills susceptible bacteria by preventing them from building cell walls. Mostly gram-positive bacteria; limited activity against gram-negative species.
What penicillin is commonly used for
- Gram-positive bacterial infections
- Wounds and skin infections
- Fin rot with a gram-positive component
Things to know
- People with penicillin allergies should wear gloves.
- Because many serious aquarium infections are gram-negative, penicillin is often paired with or replaced by another class.
- Not effective against parasites or fungi.
How it compares with other options
Penicillin is one of several classes of antibiotic used by keepers. Our comparison guide lays out which class suits which problem, and our treatment packs combine complementary classes so you have a backup ready.
Products containing penicillin
Penicillin FAQ
Is penicillin good for all bacterial infections in fish?
No. It works best on gram-positive bacteria. If the infection is gram-negative, other classes such as fluoroquinolones or tetracyclines are more commonly used.
Responsible use. For ornamental aquarium fish only. Not for human use or fish intended for food. Follow the label and consult a veterinarian when unsure.