Why Does My Goldfish Tank Smell Bad?

Often, a goldfish tank smells badly due to decaying and rotting things present in the water, such as dead plants, fish, snails and decaying food. These may remain hidden in or under some of the tank decorations, beneath the substrate or they may get caught in the water filter. Food particles or other debris get dispersed in the water and may not be that noticeable.

  1. Other Causes of Goldfish Tank Smell

    • Bad smells can emanate from a goldfish tank if the tank is overpopulated, as the filter may be unable to handle excessive waste discharged by the fish. Hence, regular maintenance is imperative in such cases to get rid of the odor. When the goldfish spawn, there may be a fishy odor, similar to a freshly caught fish, coming from the tank. However, this odor tends to disappear after a couple of hours of spawning. Algae growing along the sides of the tank can cause a bad smell to develop in the water.

    Food Remains

    • Uneaten food tends to get spoiled if it remains in the tank for a long time. Goldfish finish eating typically within two to five minutes of introducing the food into the fish tank. Hence, do not put in too much food in the tank, as it will just end up accumulating at the bottom. Also, before introducing the fish food, reverse the water filter in order to prevent it from sucking the food particles.

    Decaying Vegetation

    • If there are plants growing in the fish tank, they may end up decaying due to lack of oxygen in the water. This can cause an odor to emit from the tank. Remove plants or the parts that are rotting to get rid of the smell.

    Algae Growth

    • Algae start growing in the tank over a period of time if the water is not changed frequently. Use an algae scraper to scrape off the algae growing on the sides of the tank. Do this whenever you change the water in the tank.

    Chemical Reactions

    • If you are treating the tank with some chemicals, reaction between different chemicals can result in bad odor. Do not use household soap solutions to clean the tank, as the residues are harmful to the fish. Refrain from using unnecessary chemicals for cleaning. It is best to use just a chlorine remover.

    Goldfish Tank Maintenance

    • Change the water in the fish tank at regular intervals and clean the filters thoroughly by rinsing them to remove all the waste. Remove at least 50 percent of the water from the tank every week and fill it with fresh water. Rinse the water filter cartridges or replace them if they are too dirty. Rinse the gravel thoroughly with clean water or discard if they are too old and replace with fresh stock. Install bubble curtains to add more oxygen content in the tank.