The right substrate can have a big impact on the life of your Axolotl. Since Axolotls spend a lot of time on the bottom of the tank, it is important that the substrate is not harmful to them. In this article we will compare the different options for Axolotl substrate and their advantages and disadvantages.
The wrong substrate for Axolotl can lead to various problems, especially if Axolotl ingest parts of the substrate like pebbles or gravel while eating. Axolotls eat their food by it sucking in and it happens often that a bit of substrate also lands in their mouths. Most of the substrate is usually spat out again, however, a small part is often swallowed and travels with the food through the digestive tract.
If the substrate consists of parts that are so large that they cause problems with excretion or have sharp edges that injure the axolotl from the inside, this can lead to major problems.
A few symptoms after ingestion of too large or sharp stones are:
- Refusal to eat
- lethargy
- constipation and internal injuries and in the worst case death.
These problems can be avoided by choosing the right substrate right from the start.
The best substrate for axolotl is sand and fine gravel. Some owners also keep their axolotl on ceramic tiles or without any substrate on the bare glass bottom, but that can be stressful for the Axolotl.
1. Sand
The most popular substrate for Axolotl is fine sand*. In this case the chance of digestion problems due to ingestion is also very low and the Axolotl has no danger of hurting itself.
The sand is good for plants and it gives the tank a natural look. However, sand is more difficult to clean and it can form rotten spots.
However, if you have younger axolotls you should be more careful with both gravel and sand as substrate, as they cannot yet excrete large chunks of sand or gravel.
Pros:
- no danger of constipation due to the small grain size
- Plants can be planted
Cons:
- more difficult to clean than gravel, it can form rotten spots
2. Rounded gravel
Another option is rounded, fine natural gravel*. You should make sure that the grain size is between 1 and 3 mm, so that the axolotl can excrete the gravel without problems when it eats it.
A tank with gravel as substrate is also easier to clean than sand, as there is significantly less chance of decay forming.
Pros:
- No risk of impaction with the right grain size
- Plants can be planted
Cons:
- easier to clean than sand
- you have to pay attention that the gravel is also suitable for axolotl and does not contain sharp stones
With Gravel and sand a layer of at least 3 inches (7 cm) is sufficient, if you want to have plants in your tank that form deep roots you should use more substrate. All substrate should be washed thoroughly before adding them to the tank to remove any contamination.
How much gravel or sand do you need for your tank?
For a 20 gallon tank, the smallest size for a single Axolotl, you need around 20 pounds (10 kg) of gravel.
3. Large stones
Large stones can provide good grip for the axolotl and look decorative. But you cannot keep plants in the tank and the large stones are relatively difficult to clean.
If you choose this option you should make sure that the stones are really big enough that an Axolotl can’t swallow them. If you use smaller stones for growing axolotls, you need to replace them with larger ones.
The stones should be at least 3 times larger than the head of your Axolotl, so that he doesn’t accidentally eat them with his food. Adult axolotls can actually swallow stones up to 3cm in diameter, which then get stuck in their stomach or intestines as they cannot be excreted.
Pros:
- no danger of impaction if the stones are so big that the axolotl cannot eat them
- only perching plants
Cons:
- rotten spots can form between the stones
- does not offer the Axolotl as much hold as gravel and sand
- no plants that need substrate for rooting
4. Ceramic tiles
Ceramic tiles give an axolotl more grip than a bare glass bottom, also the probability that the axolotl swallows substrate and gets an impaction is extremely low.
Although, it’s better if you use gravel or sand as substrate.
Pros:
- no risk of impaction
- only perching plants on additional decoration
- very easy to clean
Cons:
- do not provide much grip, which can lead to stress
- no plants that need substrate for rooting
5. Bare glass bottom (no substrate)
A bare glass bottom is the easiest method to keep an Axolotl to avoid the danger of impaction. Cleaning a tank without substrate is also very easy, but many axolotl owners don’t like the aesthetics of a tank without substrate.
In addition, it can be stressful for axolotls if they can’t find a foothold on the smooth glass bottom. If the current in the tank is too strong, this can quickly stress your Axolotl and they would be much happier with sand or gravel as substrate.
Pros:
- no risk of impaction
- only perching plants on additional decoration
- very easy to clean
Cons:
- offers the Axolotl no grip, the probability that it stresses him is very high
- no plants that need substrate for rooting
Important factors of good substrate for Axolotl:
- Grain size between 1 and 3 mm
The right size of gravel or sand is important so that the substrate can pass through the Axolotl’s digestive tract without problems and without causing blockage. Otherwise, if the gravel is too large or the axolotl has eaten large stones, it can lead to an impaction, which can be fatal. - Round shape without sharp edges
To avoid internal injuries, it is important that the substrate is as round as possible and without sharp edges. - No chemicals, plastic or colored sand
Axolotls are particularly sensitive to harmful chemicals due to their permeable skin, which can come from colored sand or plastic-coated gravel.
Bad substrate choices for Axolotl
Here are a few examples of substrate you shouldn’t use in an axolotl tank, as it can cause injury or impaction.
Small stones and normal gravel
Because the Axolotl sucks his food into its mouth, it’s very likely that he swallows small stones and gravel. If the stones are too large to pass through the gastrointestinal tract without problems, impaction can occur, which can be fatal for the axolotl.
Stones with sharp edges and broken seashells
The sharp edges of stones or seashells can quickly injure the axolotl’s sensitive skin and cause wounds.
It can also lead to internal injuries if the axolotl eats the small stones.
Glass stones or beads and marbles
Although glass stones may look nice in the aquarium, they can be dangerous to axolotls. As long as the marbles and stones are not broken, they don’t have sharp edges that the axolotl can cut itself on, but if he swallows them it can cause a serious blockage.
Plastic or resin coated and colored sand
If gravel or rocks are coated with plastic or resin this can dissolve in the axolotl’s stomach and make him sick. Likewise, colored sand can release chemicals into the water and be harmful for the axolotl.
What is the best way to clean the substrate in your Axolotl aquarium?
With sand and gravel for substrate a gravel vacuum* is the tool you need. This is used to remove dirt and poop from the substrate.
Why do axolotls sometimes eat pebbles and gravel?
Some Axolotls can be observed eating small stones and gravel, why they do this is not yet conclusively understood, but there are a few theories about their behavior.
In addition to food, axolotls often take up parts of the substrate when feeding, but deliberately “eating” stones and gravel is difficult to explain at first.
One possibility is that the Axolotl confuses the pebbles with food, because they are farsighted and can only see things clearly in the distance.
Another theory is that the axolotls swallow the pebbles to use them as gastroliths. Gastroliths, or stomach stones, are stones that some animals swallow to help break down food in their stomach. It is also discussed if some aquatic animals use the gastroliths as ballast.
Whether this is really the reason why some axolotls eat stones is still discussed.
Conclusion
When choosing a substrate, in addition to aesthetics, you should make sure that its safe for your Axolotl. Also, the possibility to create a more natural environment with plants and cleaning are important factors.
Gravel or sand is usually the best option to avoid impaction and still keep plants in the tank.
If you’ve decided on a substrate, here’s an article with the top 14 plants for an Axolotl aquarium.