How to Fix a Smelly Fish Tank

Maintaining the proper balance in an aquarium is an ongoing task. The water temperature can vary, the pH and nitrate levels of the water fluctuate, and the amount of waste picked up by the filters is never the same from one day to the next. Smells emanating from your fish tank can come from a variety of sources, including dead fish, rotting food, a dirty filter or a chemical imbalance. Changing your tank's water every week is an important step in fixing a smelly fish tank.

Things You'll Need

  • Liquid dish soap or baking soda (optional)
  • Algae scraper
  • Aquarium net
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Instructions

    • 1

      Check to make sure that all of your fish are accounted for, because the smell could be coming from a dead fish or shellfish in the bottom of the tank or caught in the filter. Look to see if any food has accumulated on the surface or gotten buried in the substrate or any plants have died. Remove any excess food, dead fish or shellfish, and dead plants.

    • 2

      Check the filter for an excessive accumulation of waste material, which is an indication that either the filter is not being cleaned often enough or too many fish are in the tank. Rectify either situation by cleaning the filter more often or setting up an additional fish tank.

    • 3

      Make sure that you are changing the water at the proper intervals and at the right percentage. Extract between 20 and 25 percent of the aquarium's water on a weekly basis and substitute new, clean, conditioned water.

    • 4

      Check the labels of any chemicals that you are adding the tank's water to see if that could be causing a chemical reaction and creating the smell. Switch to a different product if necessary.

    • 5

      Check the inside of the lid to see if mold is growing, which could be contributing to the smell. Use a small amount of liquid dish soap or baking soda mixed with water to thoroughly clean the lid. Rinse the lid fully and dry it before putting it back in the aquarium.

    • 6

      Use an algae scraper to remove any algae that has accumulated on the inside of the aquarium's glass. Scoop any algae you remove using an aquarium net. Change the water within 24 hours.