Botanic Garden >> Gardening > >> Question and Answer >> Pond and Water Gardening

When to Move Koi Fry Indoors for Winter Survival

Move Now

At 10 days old (1/4 inch), they're vulnerable to dragonfly larvae, hydra, and other predators. Indoor rearing dramatically increases survival.

Indoor Setup

Tank with sponge filter (gentle flow).
Feed: Infusoria, live baby brine shrimp, crushed flake.
Commercial fry food (Hikari First Bites) works too.
Pristine water: daily 10% changes.

Outdoor Alternative

If pond is heavily planted with fine-leaved plants (hornwort), some may survive. But numbers dropping from 200 to <100 in 10 days says predation is heavy.

Pond and Water Gardening: Koi Pond Fish Die-Off: Diagnosing a Mysterious Mortality Event; Fish Dying After Pond Relocation; Koi Dying Weekly: Fungus as Secondary Infection; Fish Die-Off After Algaecide Treatment: Emergency Response; Sudden Mass Koi Deaths in Established Pond; Copper Sulfate Algae Treatment: Fish Safety First; New Preformed Pond: Goldfish Dying in Hours; Fish Kill After Tadpole Hatch: Oxygen Crash; Koi Dying One by One in a New 300‑Gal Indoor Pond: Overcrowding and Aggression?; Goldfish Lying on Side: Swim Bladder, Injury, or Infection?

Garden Articles

New Pond Fish Die-Off: Ammonia Spike from Overstocking

Winter Koi Losses in 15,000-Gal Pond: Aerator Placement and Biofilter Loss

Christmas Lights Fall in Pond: Fish Electrocution or Stress?

Overwintering Koi in Upstate NY: Indoor Aquarium Success

Missing Koi: Predators, Jumpers, and Pond Mysteries

New Pond Owner Loses Koi: Common Mistakes and How to Avoid Them

Why Your Koi Keep Dying in Winter: The Pond Is Too Small

Plants

Mysterious Fish Deaths in a Well-Filtered Pond: Troubleshooting Guide

Why Are Only Young Goldfish Dying in an Established Pond?

Overwintering Koi in a Shallow Pond (12–14 Inches Deep)

Adding Koi to a 1-Acre Stock Pond with Bass, Bluegill, Minnows

Goldfish Deaths in Converted Pool Pond: Cat Food and Oxygen

Daily Goldfish Deaths in 5-Year Pond: New Fish or Water Change?

Koi Swimming Sideways: Swim Bladder Disorder and Quarantine Treatment