Seachem KanaPlex

Seachem KanaPlex

Seachem KanaPlex is a kanamycin-based antibiotic and one of the most dependable broad-spectrum treatments in the freshwater hobby. It's the medication to reach for when a fish has a genuine bacterial infection — fin and tail rot, popeye, dropsy, columnaris, or septicemia — and it also handles some fungal infections. Crucially, it works against both gram-positive and gram-negative bacteria, which makes it a strong first choice when you can see something is wrong but can't pin down exactly what.

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.

Because it can be bound to food with Seachem Focus and fed directly to the fish, KanaPlex can treat internal infections even when a fish has stopped eating well, and it lets you medicate a single fish rather than an entire display. It does not wreck the biofilter the way some antibiotics do, and any residual is easily removed with carbon afterward.

Dosing Guidelines: Dose per the label — the standard course is one measured dose every 48 hours for three doses (about 6 days). Remove chemical filtration (carbon, Purigen) and any phosphate media before dosing, and finish the full course even if the fish looks better. Best used in a hospital/quarantine tank; KanaPlex is not reef-safe in the water column.