Adding eggshells to an aquarium is becoming increasingly popular due to so many having eggs for breakfast or with one of their daily meals resulting in them having left over eggshells that would otherwise go to waste.
Although there are a number of chemical mineralizing products that you are able to use in your aquarium, they can be pricey and many people within the fish keeping community try to keep their costs as low as possible.
This is why we have seen so many people reaching out and asking about adding eggshells to their aquarium to try and workout the actual advantages and disadvantages of the method.
Because ground up eggshells are becoming increasingly popular within the fish keeping hobby, we wanted to publish this article to try and help as many of our readers as possible better understand how you should be using your eggshells as well as how they can effect your aquarium both positively and in some cases, negatively.
Can I Put Eggshell In My Fish Tank?
The simple answer is yes, you are able to add eggshells to your aquarium.
We would however recommend that you do not add them directly to your aquarium as they can cloud the water and make it difficult for your fish to see.
Instead, what we recommend doing is boiling the eggshells for around 3-5 minutes and then crushing them into a fine powder using either a mortar and pestle or even just a coffee grinder.
Once you have turned your eggshells into a fine powder, you are then able to add them directly to your aquarium filter where they will slowly release calcium carbonate into the water which is perfect for both plant growth as well as helping to raise the pH levels in your aquarium.
It is important to note that you should not overdo it with the eggshells as too much calcium carbonate can make it difficult for fish to absorb other minerals that they need which can be detrimental to their health.

Will Eggshells Mineralize My Aquarium?
Eggshells can mineralize your aquarium offering large amounts of calcium as well as having a decent magnesium and potassium content with a number of trace nutrients in there too.
Why Do People Add Eggshell To Their Aquarium?
As we briefly touched on above, one of the main reasons why people choose to add eggshells to their aquarium is because they slowly release calcium carbonate into the water which is perfect for plant growth.
Not only this but it will also help to raise the pH levels in your aquarium making it more alkaline which many fish prefer.
If you keep snails in your aquarium then eggshells can also be a great source of calcium for your aquatic snails and to some extent, shrimp and crayfish too.
It is important to note that if you are adding eggshells to your aquarium specifically for your snails, we would recommend boiling them for a little longer (around 10 minutes) as this will help to make them easier for your snails to digest.
How Do I Add Eggshell To My Aquarium?
As we briefly touched on above, you should not add whole eggshells to your aquarium as they can cloud the water and make it difficult for your fish to see.
Instead, what we recommend doing is boiling the eggshells for around 3-5 minutes (around 10 minutes for tanks with snails) and then crushing them into a fine powder using either a mortar and pestle or even just a coffee grinder.
This presumes that you have taken the time to remove the membrane from the eggs as well as any other impurities too prior to boiling them.
Although some people leave the egg membrane in the egg as fish will eat it, the membrane can contain some potentially harmful bacteria so we usually recommend that you remove it if possible.
The boilng process not only weakens the eggshell making it easier for you to crush and your plants, snails, shrimp, and crayfish to process it but it also helps to remove the membrane and any potentially harmful bacteria too.
Keep in mind that eggshell can be sharp, even after being boiled and it may harm some fish if they eat large chunks of it. This is why you really do have to be careful when it comes to grinding the eggshell up ready for use.
Make sure that it is a fine powder with a corseness between sugar and flour prior to adding it to your aquarium to avoid issues.
Will Egg Shells Raise pH In Your Aquarium?
Eggshells have a high pH level and can help to raise the pH levels in your aquarium if the water is too acidic.
If you live in an area with hard water, then chances are the pH levels in your aquarium are already on the alkaline side and you may not need to add eggshells.
You can test the pH levels of your aquarium water using a simple test kit which you can pick up from most pet stores.
If you find that the pH levels in your aquarium are on the acidic side, then adding some eggshells could be a good idea.
Just remember not to overdo it as too much calcium carbonate can make it difficult for fish to absorb other minerals that they need which can be detrimental to their health.
When Type Of Eggshells Should I Add To My Aquarium?
Most people add regular chicken eggs to their aquarium due to them being so cheap and many people already having chicken eggs in their diet meaning that the chicken eggshell is often left over.
Although other types of eggshell can work, the mineral and more importantly pH content of the eggs can change drastically from species to species so you do have to do your own research into the specific eggs of any other birds eggs you plan to add to your aquarium.
Will Fish Eat Eggshells?
Providing that you have crushed the eggshells into a fine powder, then it is highly likely that your fish will eat them.
Many fish love eating eggshells as they are packed full of nutrients that are beneficial for their health.
Eggshells contain high levels of calcium carbonate which is perfect for plant growth and can also help to buffer the pH levels in your aquarium.
Calcium is also necessary for the development of strong bones and fins in fish as well as helping them to produce a strong eggs if they are spawning.