Health & WellbeingCan one freshwater fish with ich kill all my freshwater fish? Cause last night after my husband cleaned their tank one kept dying after another.
If left untreated, ich will eventually kill. It can weaken the fish after which infection will set in and finish it off.
It is also possible the fish were killed if a water change was done as part of the cleaning. Aged or conditioned water should always be used to avoid exposing fish to harmful chemicals, mainly chloramines, many municipalities use in treatment. Water that is not temperature matched can cause shock which will also kill fish.
If can be treated by gradually raising the water temperature over 24 hours to about 85 F. Ich is temperature sensitive, this the warm water will speed up the life cycle. Once the "dots" fall off your fish, vacuum the substrate and then use a commercial ich treatment. Leave the temp at 85 F for 2-3 weeks to clear the tank. Afterwards, gradually decrease temperature to the proper temperature for your species of fish.
Updated on August 12th, 2025
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