Seachem NeoPlex

Seachem NeoPlex is a broad-spectrum antibiotic powder built to treat the most common bacterial infections in both freshwater and saltwater fish. It works against external infections like fin rot, columnaris, mouth fungus, and eye cloud, and can be combined with Seachem Focus to deliver the medication internally through food. Browse all aquarium medications.

What It Treats

• Hemorrhagic septicemia, dropsy, and secondary infections from injury
• Fin and tail rot
• Columnaris and mouth fungus
• Eye cloud and popeye
• Gill disease
• Bacterial slime coat disorders

Why Hobbyists Use NeoPlex

• Both fresh and salt. One bottle covers your freshwater community tank and your hospital-tank saltwater fish.
• Pairs with Focus. Designed to be food-bound with Seachem Focus for internal delivery, which is the most effective way to dose a still-eating fish.
• Hospital-tank friendly. Dose in a quarantine or hospital tank to protect biofilter and inverts in your display.
• Trusted brand. Seachem's reputation for accurate dosing, clean ingredients, and consistent results.

How to Dose

In water (bath treatment): 250 mg (one measure) per 10 gallons every 24 hours. Maintain treatment for 5 days or until symptoms clear, whichever is sooner.

In food (internal treatment, preferred for active feeders): Mix 5 measures of NeoPlex with 1 measure of Focus into the desired weight of food. Re-feed daily as long as the fish eats.

Important: Remove activated carbon and other chemical filtration during treatment. Run fresh carbon and perform a 20 percent water change after the course is finished.

Specifications

Recommended Pairings

• Seachem Focus — food binder for internal delivery
• Seachem MetroPlex — rotate or stack for protozoan coverage
• Seachem KanaPlex — gram-negative bacterial coverage
• Seachem Prime — for the post-treatment water change
• All aquarium medications

FAQ

Will it kill my biofilter?
Like most aquarium antibiotics, NeoPlex can stress nitrifying bacteria. Treat in a hospital tank or watch ammonia and nitrite closely if you must dose the display.

Is it safe with inverts?
No. Snails, shrimp, and other inverts can be sensitive to neomycin. Move them out before treating, or use a hospital tank.

How do I know it is working?
External symptoms (fin damage, cloud, slime) should start to stabilize within 2 to 3 days. If the fish is still actively eating, the food-bound Focus method delivers the antibiotic directly to the infection.

Can I use it with MetroPlex or KanaPlex?
Yes, hobbyists commonly stack NeoPlex with MetroPlex (and Focus) to cover both bacterial and protozoan infections in one treatment course.