How to Clean an Aquarium After Ich Kills a Fish

Ich, a common fish disease, can easily destroy an entire aquarium population if not caught early and treated properly. The parasite causing this condition advances rapidly and will spread from fish to fish in a matter of weeks or less. While prevention is the best cure, you can take steps to safely and completely eradicate ich from your tank once fish have fallen ill.

Things You'll Need

  • Fish net
  • Quarantine tank
  • Malachite green or formalin
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Instructions

    • 1

      Catch all surviving fish with a fish net, and remove to a separate quarantine tank immediately.

    • 2

      Raise the temperature in both tanks to 80 degrees. Higher temperatures encourage faster development of the parasite and will shorten its lifespan. Ich will run its life course and die without fish to feed off of in the old tank in two to four days. Do not put any fish back into the tank at this time. No additional cleaning should be needed after the four-day mark.

    • 3

      Purchase an ich treatment product containing malachite green or formalin. (If using formalin, be sure that the product is new because old formalin can become toxic to fish.)

    • 4

      Treat the quarantine tank according to the dosage instructions on the particular brand of ich medication you purchased. Do not exceed this dose.

    • 5

      Add your fish back to their old tank only when you are certain that all ich has been safely eradicated.

    • 6

      Determine the cause of the initial outbreak (if possible) and work to prevent a similar occurrence in the future. The introduction of new fish can often allow the parasite in, but it will rarely take hold in healthy, strong fish; stressed and unhealthy animals are much more likely to succumb to the parasite. Always quarantine new fish for two weeks to watch for signs of ich and other illness before introducing them into your main tank.