Pond wintering
wintering norms: depth, oxygen, ice cover, overgrowth, pond preparation
Pond wintering
Depth:
Wintering pond — minimum 2–2.5 m of unfrozen layer; shallowing = winterkill.
Oxygen:
Critical minimum 2–3 mg/l; below — winterkill. Check weekly under ice.
Ice cover:
Cut holes (1 per 0.5–1 ha), clear snow off ice — snow blocks photosynthesis.
Aeration:
Aerators/pumps to mix layers; at low oxygen — water exchange or aeration.
Overgrowth:
>30% vegetation = nighttime oxygen deficit; remove pondweed/elodea before winter.
Preparation:
Feed fish until +4°C water; stock wintering pond per norm; drain-check the pond.
Spring exit:
At thaw — control dissolved organics (bloat, rot) — spring kill is most common.
Market fish:
Market fish winters separately from replacement young — different density norms.