Koi Salt Treatment Dose: Exact Concentrations and Calculations

By KoiQuanta Editorial Team|Updated Mar 2026

The direct answer: Standard quarantine maintenance dose is 0.3% salinity - 2.5 lbs of non-iodized salt per 100 gallons of water. For active parasite treatment, use 0.5% - 4.2 lbs per 100 gallons. Always build up slowly over 48-72 hours.

TL;DR

For active parasite treatment, use 0.5% - 4.2 lbs per 100 gallons.
Example: 300-gallon tank at 0.3% (7.5 lbs total salt).
That's 25% × 7.5 lbs = 1.9 lbs of salt removed.
Add 1.9 lbs dissolved in a bucket to maintain concentration.
For standard quarantine: 0.3% (2.5 lbs non-iodized salt per 100 gallons).
For active parasite treatment: 0.5% (4.2 lbs per 100 gallons).
Build up over 2-3 days - don't add the full dose at once.

Salt Dose Reference Table

|---------|-----------------|-----------------|-----------------|-----|

| 0.1% | 0.8 lbs | 2.5 lbs | 4.2 lbs | Acclimation, minimal stress relief |

| 0.2% | 1.7 lbs | 5.0 lbs | 8.3 lbs | Moderate osmotic support |

| 0.3% | 2.5 lbs | 7.5 lbs | 12.5 lbs | Standard quarantine maintenance |

| 0.5% | 4.2 lbs | 12.5 lbs | 21 lbs | Active parasite treatment |

| 3.0% | 25 lbs | 75 lbs | 125 lbs | Short dip only (3-5 minutes) |

How to Build Concentration Safely

Never add the full dose at once. Rapid osmotic change stresses koi even when the target concentration is appropriate.

For 0.3% target - 3-day build:

Day 1: Add 1/3 of total dose (bring to 0.1%)
Day 2: Add 1/3 of total dose (bring to 0.2%)
Day 3: Add final 1/3 (reach 0.3%)

Dissolve each portion in a bucket of tank water before adding. Don't pour granular salt directly on fish.

Replacing Salt After Water Changes

Water changes dilute salt. Calculate and replace the amount removed.

Example: 300-gallon tank at 0.3% (7.5 lbs total salt). 25% water change removes 75 gallons. That's 25% × 7.5 lbs = 1.9 lbs of salt removed. Add 1.9 lbs dissolved in a bucket to maintain concentration.

What Salt Works For

Osmotic stress relief (fish with compromised skin or gill damage)
Trichodina and Costia (protozoan parasites)
Reducing bacterial secondary infection risk on wounds
Post-show prophylaxis

What Salt Doesn't Treat

Flukes (need praziquantel)
KHV (no treatment exists)
Ich in isolation (needs heat or medication)
Anchor worm or lice (need targeted treatments)
Bacterial infections (need antibiotics)

FAQ

What is the correct koi salt treatment dose?

For standard quarantine: 0.3% (2.5 lbs non-iodized salt per 100 gallons). For active parasite treatment: 0.5% (4.2 lbs per 100 gallons). Build up over 2-3 days - don't add the full dose at once. Use non-iodized salt only.

Can I use table salt for koi treatment?

No. Table salt contains iodine and anti-caking agents that are harmful to koi and filter bacteria. Use non-iodized rock salt, kosher salt, or pool-grade sodium chloride without additives. Pool salt (sodium chloride, no other additives) sold in 40 lb bags is a cost-effective choice for larger operations.

How long do I keep salt in the quarantine tank?

Maintain salt at 0.3% for the full quarantine period - typically 21-42 days. When quarantine ends and you're ready to move fish to a display pond without salt, reduce concentration gradually over 1-2 weeks through water changes rather than stopping abruptly.

What is Koi Salt Treatment Dose: Exact Concentrations and Calculations?

Koi salt treatment dosing refers to the practice of adding non-iodized salt to pond or quarantine water at specific concentrations to support fish health. The standard maintenance dose is 0.3% salinity — about 2.5 lbs of salt per 100 gallons. For active parasite treatment, the concentration increases to 0.5%, or 4.2 lbs per 100 gallons. Concentrations are always built up gradually over 48–72 hours to avoid osmotic shock.

How much does Koi Salt Treatment Dose: Exact Concentrations and Calculations cost?

Koi salt treatment has no monetary cost beyond the price of non-iodized salt, which is widely available and inexpensive. A 50 lb bag typically costs under $15 at feed or agricultural supply stores. There are no proprietary products required — plain, non-iodized salt is the correct choice. Iodized table salt or salt with additives should be avoided, as these can harm koi and disrupt pond biology.

How does Koi Salt Treatment Dose: Exact Concentrations and Calculations work?

Salt treatment works by raising the salinity of the water, which reduces the osmotic stress on koi by equalizing the salt gradient between the fish's body and its environment. At 0.3–0.5%, elevated salinity also disrupts the life cycle of common parasites like ich and flukes, which cannot tolerate the changed water chemistry. Salt is dissolved in a bucket of pond water first, then added slowly in stages over two to three days.

What are the benefits of Koi Salt Treatment Dose: Exact Concentrations and Calculations?

Salt treatment benefits koi in several ways: it reduces osmotic stress, supports gill function, promotes slime coat regeneration, and creates a hostile environment for many external parasites. It is particularly useful during quarantine, after injury, or when parasites are suspected. Because it is natural and non-toxic at correct doses, it is one of the safest and most accessible interventions available to koi keepers of any experience level.

Who needs Koi Salt Treatment Dose: Exact Concentrations and Calculations?

Any koi keeper managing a quarantine tank, treating a sick or stressed fish, or dealing with common parasites like ich, flukes, or costia should understand proper salt dosing. It is especially relevant for new pond owners introducing fish, hobbyists experiencing unexplained fish losses, or anyone without immediate access to prescription treatments. Proper dosing knowledge prevents both underdosing — which is ineffective — and overdosing, which can be harmful or fatal to koi.

Sources

Associated Koi Clubs of America (AKCA)
Koi Organisation International (KOI)
University of Florida IFAS Extension Aquaculture Program
Fish Vet Group
Water Quality Association