Koi with Dark Red Gills: Emergency Water Quality Fix

Ammonia/Nitrite Poisoning—Act Now

4 koi dead in 2 weeks, survivors have dark red gills (classic ammonia/nitrite burn).

Immediate Protocol

1. Test ammonia & nitrite NOW. If >0, proceed.
2. 50% water change with dechlorinator (match temp/pH).
3. Stop all feeding until ammonia/nitrite = 0 for 3 days.
4. Add MelaFix for gill healing.
5. Test daily and repeat 30% changes until levels stay zero.
6. Add bottled bacteria (Nitrospira/Nitrosomonas) to jump-start biofilter.

Root Cause

• Overfeeding, overstocking, new filter, dead fish decay, or chloramine in tap water.
• Fix the cause or it will recur.

Red gills = chemical burn. Water changes are the only cure.