Fish Pen Penicillin 500mg – 30 Tablets

Fish Pen (Penicillin) 500mg Tablets are a reliable, fast-acting treatment for gram-positive bacterial infections in aquarium fish. Designed to combat conditions such as fin rot, columnaris, gill disease, and skin ulcers, this broad-spectrum antibiotic helps restore health and vitality to your aquatic environment.

Formulated for both freshwater and saltwater aquariums, Fish Pen dissolves quickly in tank water for rapid absorption. It’s a trusted solution used by aquarists, breeders, and aquatic veterinarians to contain infections and prevent bacterial outbreaks.

Key Benefits

• Boad-Spectrum Antibiotic: Targets gram-positive bacteria including Streptococcus and Aeromonas species.
• Ideal for Common Infections: Effective for treating fin rot, gill disease, columnaris, and body ulcers.
• Fast Action Formula: Rapid dissolution supports quicker results without clouding the water.
• Safe for Ornamental Fish: Formulated to work with most freshwater and saltwater species.
• Easy to Use: No mess, no guesswork—precise 500mg dosing per tablet.

How to Use Fish Pen (Penicillin) Tablets

• Use 1 tablet (500mg) per 20 gallons of aquarium water.
• Repeat dosage every 24 hours, with a 25% water change before each dose.
• Treatment duration: 5 to 10 days, depending on severity of the infection.
• Use in a separate hospital tank to minimize impact on bio-filtration.

Precautions & Warnings

• For aquarium use only. Not for human consumption or use in food fish.
• Remove invertebrates (shrimp, snails, crabs) prior to treatment.
• Monitor ammonia and nitrate levels during use to ensure stable water quality.
• Do not overdose. Follow dosing based on tank volume.

Storage Instructions

• Store in a cool, dry place at 59°–86°F (15°–30°C).
• Keep sealed to protect from moisture and sunlight.
• Check expiration date before use for optimal effectiveness.

Shipping & Returns

Shipping: We offer Ground, Priority, Express, and International shipping. View full shipping policy here.

Returns: If you're not satisfied, review our refund and return policy before requesting a return.

FAQs – Fish Pen (Penicillin) 500mg for Aquarium Fish

What does Fish Pen treat?

Fish Pen treats bacterial infections caused by gram-positive bacteria such as fin rot, columnaris, gill disease, and skin ulcers.

Can it be used in saltwater tanks?

Yes. Fish Pen is safe for both freshwater and marine aquariums when used as directed.

Will Fish Pen harm the biological filter?

It may affect beneficial bacteria. Use in a hospital tank to protect your main system's filtration.

Is Fish Pen safe for planted tanks?

Generally yes, but always remove sensitive species and monitor plant health during treatment.

Can I use it with invertebrates?

No. Remove shrimp, snails, and other inverts before dosing. Penicillin may be harmful to them.

Is it safe for small tanks or bettas?

Yes, but calculate exact dosage based on tank size to avoid overdosing.

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