Cuttlefish bone contains approximately 85% calcium carbonate, making it a great source of calcium. Due to its mineral composition, it is often placed in the enclosures of some pets to aid in the supplementation of the calcium. If you’re keeping goldfish, betta fish, or other types of pet fish, you can use this type of bone for a healthier aquarium. But why should you put cuttlebone in your aquarium?
You can add cuttlebone into your aquarium as a source of calcium or as a way of regulating the kH and pH of the water. Fish require calcium for egg development and bone growth. The bone also acts as a periphyton settlement that provides plankton to aquarium fish.
But, this bone is fragile and floats on water due to its buoyancy, which makes it difficult to keep in the aquarium at the proper depth. In fact, some pet fish owners think it is dangerous to have this bone in most freshwater aquariums – which is not the case if properly done.
Cuttlebone is made of aragonite, which is a form of calcium carbonate. Calcium is important in freshwater aquariums because it helps fish, snails, and other aquatic animals grow, produce healthy eggs, and even improve the integrity of their shells. Adding cuttlebone in your aquarium is, therefore, an inexpensive way to slowly add calcium to your fish tank.
Here are the benefits of putting cuttle fish bone in your fish tank:
1. It helps maintain water hardness (kH)
The calcium in the cuttlebone is great for maintaining proper water hardness. It helps absorb the excess nitrates and nitrites produced in the freshwater fish tank that by extension helps keep the water safe for your fish.
If your aquarium water has a low kH, adding cuttlebone can help improve the kH and the water’s buffering qualities.
As a result, it becomes easier to control and maintain the aquarium’s pH in a range that’s safe for the type of fish you’re keeping.
A single gram of bone dissolves in water to yield 1.5 grams of Bicarbonate, equivalent to 15 mg/L of Calcium Bicarbonate, when added to a 100-liter aquarium.
Calcium bicarbonate (Ca(HCO3)2) contains 75% bicarbonate and 25% calcium, making it a carbonate salt (also known as “calcium salt”). With every 2 grams of cuttlefish bone you add to the water, you’re increasing the dKH by approximately 1.
2. Cuttlebone helps maintain aquarium pH levels
Since cuttlebone aids in treating water hardness, it also helps improve its buffering ability. For most aquariums, crushed corals or calcium carbonate-based gravels are used as substrates to constantly improve the water’s buffering ability.
You can also add cuttlefish bone to your fish tank as an alternative to other carbonate and bicarbonate additives. Since buffering capacity and pH are intertwined, improving the water’s buffering ability also improves the aquarium’s pH stability.
If your driftwood produces tannins in your tank that lower water pH, cuttlebone can help neutralize that effect.
3. It helps with egg development
Calcium is an important mineral in the development of eggs in fish. Since the development of eggs occurs outside the fish’s body, its mineral content is very important for maturity and integrity.
A study by Chatakondi, Nagaraj and Jeffers Carl of the USDA Agricultural Research Service found that “Calcium alone or in combination with Magnesium in hatching waters facilitates egg development.“
3. It improves the health of your fish
Cuttlebone is high in potassium, iron, zinc, and chlorides. These vital minerals help your fish grow more quickly and live a healthier life. Despite feeding your fish a calcium-rich diet, you can still supplement the mineral using cuttlebone especially if you have, say, a number of fish in a 20-gallon tank competing for food.
You can cut, grind, or powder cuttlebone to your desired size, amount, and shape before placing it in your aquarium to not only make the water taste better but also provide mineral nourishment for your fish.
4. Cuttlebone improves bone growth in fish
Calcium is a major nutritional component for bone growth and development. A lack of this mineral can easily result in slow growth, and general weakness in your aquarium fish.
Cuttlefish bone is soft on the inside and hard on the outside. By placing it in the tank, the pet fish can nibble on the soft side and ingest the calcium directly. The other hard side of the bone can dissolve slowly into the water, thus, providing a steady supply of calcium to your fish.
4. It maintains the biological balance in your aquarium
Cuttlebone is a natural source of calcium, which can help to maintain the carbonate hardness in your tank. As a result, it will hold the biological equilibrium in your aquarium and keep unhealthy organisms away.
5. Cuttlebone enhances aerobic bacterial growth
Cuttlebones offer an excellent surface for bacterial cultures to flourish on since they are porous and contain salt ions (Ca+, Mg+, and K+). This will encourage the existence of helpful bacteria in your aquarium.
6. Cuttlebone improves shell quality
If you notice malformed snail shells, it is a sign that there’s a calcium deficiency. Adding cuttlebone or other calcium sources such as eggshells can help fix malformed gastropods.
Calcium and mineral deficiencies affect shell quality, resulting in shells breaking off easily.
In summary, cuttlebone has a high level of calcium that’s great for adjusting the kH levels in your aquarium and help your fish remain healthy. As such, it’s a natural cost-effective way to adding calcium and improving the buffering capacity of your fish tank. It also helps regulate the pH level of the water.
Pro tip: Cuttlebones are extremely delicate and shatter easily. If your fish and aquarium snails have sharp teeth, it’s best to break the cuttlebone into tiny pieces rather than using whole cuttlebones. Otherwise, it might not absorb the necessary amount of salt ions.
Every once in a while, you might experience low kH levels in your aquarium. Various reasons (such as Allophanes) mostly cause it. Cuttlefish bone has a great natural ability to absorb the excess salt and improve the calcium supply in the fish tank.
But, how much cuttle fish bone should you add into your aquarium?
On average, you can add a quarter to half a teaspoon of cuttlebone into a 10-gallon aquarium but that amount can vary depending on other factors such as the number of fish in the tank and the filtration system.
A good rule is to start with a small amount and add more if it doesn’t seem enough. You can always add more cuttlebone later on if needed.
There is a wide range of opinions on the correct amount of cuttlebone to add to an aquarium. However, there’s no right or wrong answer. It’s mostly determined by:
- The size of your tank– If you have larger, bulkier fish in your aquarium, you will need to add additional cuttlebone because bigger fish require more calcium for their developing body mass. For example, a 10-gallon tank requires approximately 1/4–1/2 teaspoon cuttlebone for the fish.
- The number of fish in the aquarium– More fish means more waste, resulting in an unbalanced biological system. If you have much fish in your aquarium, add cuttlebone and additional calcium sources such as calcium additives. Before acquiring cuttlebone, verify the nutritional guidelines of your new pets.
- The filtration – Since cuttlebones dissolve into calcium carbonate, it will affect the pH levels in your aquarium water. But don’t worry; this will not change your filters’ performance! Instead, you may need to clean them more frequently.
Caution: Watch your fish closely after adding cuttlebone to the tank. If there’s change in behavior, such as the fish floating at the top of the tank suddenly, or change in the color and behavior, you want to consult a fish vet as soon as possible.
No, cuttlebone does not hurt fish and is an excellent source of calcium for them. It contains natural minerals and nutrients that will benefit your fish’s bone structure and internal organs.
When you drop the cuttlebone into the aquarium, the fish may taste it and consume a lot of bone powder.
The most minimally invasive method is to powder the bone with the lights off. Fish sleep at night while snails roam about eating whatever bone they can find.
Yes. Cuttlebone is a type of shell that will dissolve into calcium carbonate that will change your tank’s pH levels. This is a chemical reaction between the acid and the calcium carbonate; therefore, it does not affect your filter’s performance.
In small doses, it will not increase water pH at all. In larger amounts, cuttlebone can change the pH slightly over a few days.
You can use cuttlebones as part of your fish diet or as decoration for aquariums to provide them with the natural minerals they need for good health, such as calcium and magnesium.
Some fish keepers believe they help reduce aggression among male bettas (Siamese fighting fish also used them).
READ NEXT: BEST MIDGROUND AQUARIUM PLANTS
- Duke University: What do you need to know about water chemistry and why?
- Madhumita Das et al, Visakhapatnam Regional Centre of CMFRI: Utilization of cuttlebone by aquafarmers at Visakhapatnam