Salt Concentration Guidelines for Fish Tanks

 

1. Basic Formula

The standard calculation method is:
Salt amount (grams) = Water volume (liters) × Concentration (‰)
For example:

  • 100L water × 0.3‰ = 30g salt (preventive use)
  • 100L water × 0.5‰ = 50g salt (mild disease treatment)

2. Concentration Ranges by Purpose

Scenario

Salt Ratio (‰)

Duration

Notes

Prevention/Stress Relief

0.1-0.3

3-5 days

Ideal for new fish acclimation

Mild Disease (e.g., Ich)

0.3-0.5

30-minute baths or 3-day treatment

Combine with +2℃ temperature rise

Severe Infections

0.6-0.8

Max 3 days

Requires quarantine tank

3. Critical Notes

  • Salt Type: Use aquarium salt (avoid iodized table salt).
  • Measurement: 1‰ = 1g salt per 1L water (ignore minor water density errors).
  • Species Sensitivity:
    • Freshwater fish: <0.5‰ long-term.
    • Brackish fish (e.g., mollies): 1-1.5‰.
    • Saltwater fish: 30-35g/L (not applicable to freshwater setups).
  • Water Changes: Replace 1/3 water after 3-5 days of salt treatment.

4. Common Mistakes

  • Overestimating salt's effectiveness (not a substitute for medication).
  • Neglecting to dissolve salt before adding (always pre-mix in warm water).
  • Ignoring salt-sensitive plants (avoid >0.05‰ in planted tanks).