Baby Koi & Paracide Green: Treatment Risk

Pond fish brought inside for winter. One koi sick, moved to separate tank, both tanks treated with Paracide Green. Asks if baby koi affected.

Paracide Green = Malachite Green + Formalin

Kills parasites. Highly toxic to fry/juveniles. Baby koi have immature gills/livers—lower tolerance.

Critical Questions

1. Confirmed parasites? Scrapes + microscope. Treating blindly risks chemical poisoning.
2. If bacterial: Paracide won't help; need antibiotic.
3. Safer alternative: Salt bath (0.3% for 3–5 days) for external parasites—gentler on babies.

Every chemical adds stress. Diagnose first. If parasites confirmed, salt bath is preferred for juveniles. Isolate sick fish; don't treat whole system unless outbreak confirmed.