Can We Add Eggshells to Aquarium?

Aquarium enthusiasts are always looking for ways to improve the health and vitality of their aquatic pets. One unconventional approach that has been suggested is adding eggshells to the aquarium water. At first, this may seem strange, but it is important to keep in mind the potential advantages and disadvantages of this practice. In this article, we will explore whether adding eggshells in aquariums is a good idea, and if yes, then how to do it properly.

Benefits of Adding Eggshells to Aquarium

Calcium Supplement

Eggshells are enriched with calcium, a vital nutrient for many aquatic species. Adding crushed eggshells can help maintain healthy bone and tissue growth in fish, as well as promote the development of healthy eggs in breeding pairs.

pH Stabilization

Eggshells are alkaline, which means they can help to stabilize the pH level of the aquarium water. This is especially beneficial for species that require a slightly alkaline environment, such as African cichlids.

Beneficial Microbes

Eggshells contain a variety of beneficial microorganisms that can help to establish a healthy biological balance in the aquarium. These microbes can aid in breaking down waste products, reducing ammonia levels, and improving water quality overall.

How to Add Eggshells to Aquarium


Before adding eggshells, it is important to prepare them properly. This involves washing the shells thoroughly with warm water to remove any remaining membrane or residue. The shells should then be boiled for several minutes to sanitize them and kill any potential pathogens.


Once the eggshells have been prepared, they should be crushed into small pieces using a mortar and pestle or a food processor. The shells should be crushed into small enough pieces so that they can easily dissolve in the water, but be careful, they should not be crushed like a powder.

Adding to the Aquarium

Crushed eggshells can be added directly to the tank water, or they can be hung in the water in a mesh bag or nylon stocking. It is critical to gradually add the shells to prevent abrupt changes in pH or calcium levels. One teaspoon of crushed eggshells per ten gallons of water is a reasonable rule of thumb.

Drawbacks of Adding Eggshells in Aquarium

pH Imbalance

While eggshells can help to stabilize the pH level of the aquarium water, they can also cause an imbalance if added in excess. This is because they are highly alkaline and can raise the pH level too much if added in large amounts. This can be harmful to certain species that require a specific pH range.

Water Hardness

Eggshells can also increase the hardness of the aquarium water, which can be detrimental to some species. For example, soft water species such as tetras and angelfish may not thrive in water that is too hard.


In conclusion, adding eggshells to an aquarium can be a beneficial practice if done correctly. It can provide a source of calcium, stabilize pH levels, and introduce beneficial microbes to the water. However, it is important to take into account the potential disadvantages such as pH imbalances and water hardness. Before adding any aquarium supplement, it is always best to get knowledge and consult with a professional before adding anything to your aquarium.


Can eggshells make my aquarium water too hard?

Yes, eggshells can increase the hardness of water if added in excess. It’s essential to monitor the water’s hardness and adjust accordingly.

How often should I add eggshells to my aquarium?

It’s best to add crushed eggshells gradually over time and monitor the water parameters. You may only need to add eggshells once every few weeks, according to the needs of your tank.

Can eggshells introduce harmful pathogens to my aquarium?

Eggshells can carry pathogens, boil them for several minutes before adding them to the tank, it will help to sanitize them.

Can eggshells cause cloudy water in my aquarium?

If the eggshells are not crushed finely enough, they can cause cloudiness in the water. It’s important to crush the eggshells into small enough pieces so that they can easily dissolve in the water.

Can eggshells harm certain species of fish or aquatic plants?

Yes, eggshells can cause harm to certain species that require specific pH or water hardness levels. It’s important to research the needs of your water tank species before adding eggshells

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