Is white spot on fish contagious?

Yes. White spot disease (Ich) is highly contagious among fish.

It is caused by the parasite Ichthyophthirius multifiliis, which spreads quickly in an aquarium. Once a fish is infected, the parasite drops off into the water, multiplies, and then reinfects the same fish or spreads to others. Even fish that don’t show spots yet may already be infected.

Key points:

• Spreads rapidly in shared water
  

• Stress (poor water quality, temperature swings, new fish) increases susceptibility
  

All fish in the tank should be treated, not just those with visible spots

What to do immediately:

• Begin treatment for the entire aquarium
  

• Raise temperature gradually (if species tolerate it) to speed up the parasite’s life cycle
  

• Improve water quality and reduce stress
  

• Quarantine new fish in the future

Other Common Questions:                                                                                                         Can White Spot Treatment Kill Aquarium Fish?                                                            Effective Treatment for White Spot Disease                                                                              Is white spot on fish contagious?

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Effective Treatment for Ich - White Spots on Freshwater Aquarium Fish