How Salt Helps Freshwater Fish Stay Healthy

Reduces Stress

Salt helps fish maintain a proper fluid balance (osmoregulation), especially when they’re stressed by handling, shipping, or changes in water quality.

It reduces the energy they expend trying to keep their internal salt levels balanced, which helps them recover faster.

Supports Gill Function

A low concentration of salt in the water can improve gill function, making it easier for fish to absorb oxygen—especially useful when water quality isn’t ideal.

Kills Parasites and Pathogens

Salt can help eliminate certain external parasites (like costia, ich, and flukes) and bacterial infections on the skin and fins.

It acts as a mild antiseptic and creates an unfavorable environment for some harmful microorganisms.

Promotes Mucus Coat Health

Salt can stimulate the production of a healthy slime coat, which is a natural protective barrier against disease and injury.

Aids in Recovery

It's often used in quarantine tanks or treatment baths to help koi recover from illness, wounds, or infections.

Use Salt with Caution

Too much salt can be harmful, especially to plants, snails, and certain sensitive fish species.

Always measure carefully (usually 0.1%–0.3% concentration for general use).

Use pure, non-iodized salt made for aquariums or ponds—never use table salt with additives.