Koi Die-Off After Heavy Rain; Turtle Pond Water Quality Issues

After heavy rain, all koi died in a pond with one turtle and minnows. Water turns brown, filter clogs fast, "maggot-like" critters in filter.

Rain-Induced Fish Kill

Sudden influx of cold, low-oxygen, or pollutant-laden runoff can shock fish. Small or poorly aerated ponds are most vulnerable.

Brown Water & Filter Sludge

With koi gone, turtle waste is now the primary bioload. Turtles are messy; upgrade filtration significantly. "Maggots" are likely insect larvae (midges, crane flies)—harmless but indicate high organic load.

Action Plan

1. Test water: ammonia, nitrite, nitrate, pH.
2. Install larger filter (e.g., bead filter, bog filter).
3. Add aeration.
4. Remove excess sludge manually.
5. Identify turtle species for specific needs.

See turtle pond guide.