Seachem NeoPlex

Seachem NeoPlex

Seachem NeoPlex is a neomycin-based antibiotic, another member of Seachem's powdered -Plex line. Neomycin is especially valued for stubborn gram-negative bacterial infections — the tough, hard-to-shift bugs behind many cases of fin rot, ulcers, and similar conditions that don't respond to milder treatments. It's effective in both freshwater and marine systems.

A quick primer: bacteria are split into two broad groups by the structure of their cell wall, which is what a "Gram stain" reveals. Gram-positive bacteria have a thick outer wall that holds the stain (they appear purple); Gram-negative bacteria have a thin wall behind an extra outer membrane (they appear pink) and are generally tougher to treat. Most of the nasty infections aquarium fish get — fin rot, columnaris, dropsy, septicemia — are gram-negative, which is why the antibiotic you choose matters: a drug that only hits gram-positive bugs won't touch a gram-negative infection.

Like the rest of the line, NeoPlex can be dosed in the water or bound to food with Seachem Focus for internal infections and for treating individual fish. It's a useful alternative or complement when a gram-negative infection proves persistent, and it gives experienced fishkeepers another tool when first-line treatments fall short.

Dosing Guidelines: Dose per the label, completing the full course. Remove chemical filtration (carbon, Purigen) before dosing, and treat in a quarantine tank where possible. As with all antibiotics, avoid under-dosing or stopping early, which encourages resistance.