Substrate is what is added on the bottom of your axolotl’s cage. Axolotls have a delicate skin, and they are also curious, so you must choose a substrate carefully. This is to avoid injury and ingestion when feeding. In this post, you will find safe axolotl substrate ideas, best safe options and bad options to avoid.
Best axolotl substrate ideas and options are fine smooth natural sand, bare bottom, large rocks, tile. A mix of substrates will also work, but is more work to clean.
Best substrate for axolotls
#1: Natural sand
Natural fine sand is one of the best substrate options for an axolotl cage. While sand does pose a risk of ingestion and impaction, you can minimize the risk by choosing clean fine natural sand. You can also use washed playsand.
There are different types and grades of sand. Avoid calcium carbonate sand (sand for reptile tanks, marine sand), as it can disturb pH levels in the tank (potentially raise them too much).
If you decide to use sand, please make sure to stir it up once a while. That’s because if you don’t, air pockets will develop inside the sand layer and cause buildup of gases and bacteria. You will need to clean it using an aquarium siphon with good suction like this.
Acceptable sand type:
- Pure aquarium sand without dyes like this
- Silica sand
- Playsand
- Aquarium filter sand
- Estes Stoney river like this
Bad sand type options for axolotls – avoid:
- Sharp sand, such as construction sand
- Sparkly sand (crushed rock)
- Quartz sand
- Marine sand (high calcium carbonate)
- Reptile tank sand (made from calcium carbonate)
- Sand with argonite (calcium carbonate)
- Sand containing magnetite
- Colored sand – might make water cloudy, and can even be toxic
Only fine natural sand can be used, to prevent any skin damage and impaction. Make sure to rinse the sand before adding to the tank.
Don’t use sand for baby axolotls that are under 6 inches/15 cm long. Older axolotls often pass sand that they ingest, and usually spit it out if swallowed with food.
#2: Large rocks/gravel
Small gravel and rocks must not be used in an axolotl’s cage. That’s because axolotls suck in their food and swallow it. If rocks are too small, your axolotl will also ingest them with food.
That will cause intestinal blockage, which is often lethal. However, gravel/rocks provides good grip for your axolotl to move around.
Larger rocks pose a smaller risk of your axolotl swallowing them. If you decide to use rocks, make sure they are 2-3 times larger than the diameter of your axolotl’s head, like these large ones.
Rocks/gravel must be smooth and rounded, without any sharp edges to prevent skin injury (axolotl skin is delicate). You can also go for slate stones instead. Rocks are not the best choice of substrate, as the risk is still there. Don’t use any type of gravel/rocks with baby axolotls under 6 inches/15 cm long.
If you decide to go with gravel/rocks, get ones for aquariums. That’s because general gravel from building shops etc. might contain salts and other chemicals that will affect water quality.
You can also glue down rocks to avoid any risk of ingestion. To glue them down, you can use aquarium-safe silicone like this. However, make sure not to leave any space on the bottom or create slopes, as it will harbor bacteria inside and waste will get trapped there.
#3: No substrate at all/bare bottom
If your axolotl is still a baby, you can leave a tank bottom bare and not use any substrate at all. Having no substrate at all makes cleaning and maintenance much easier.
However, this is not the best idea for an older axolotl, which has properly developed legs. That’s because a bare bottom will not provide enough grip and will stress your axolotl.
Pros of a bare bottom in an axolotl tank is that it’s much easier to see and remove uneaten foods. This will make it easier to maintain good water quality too.
Cons of having a bare bottom is that it won’t be too aesthetically pleasing and won’t provide enough support for your axolotl to move around. Plants will also have to be free-floating. However, if you cover the bottom of the cage with enough plants and few large pieces of slate, it might be enough to provide support.
#4: Tile
Another substrate idea for an axolotl enclosure is tile. Slate/ceramic/kitchen backsplash tiles are one of the most popular options if choosing this substrate type.
Tile might not be the softest on the bottom, but it provides some grip and is easy to clean. It always removes any risk of impaction that rocks or sand pose. Avoid vinyl, linoleum (might be toxic), or very smooth tiles (won’t provide grip).
Make sure to silicone down the slate tile before adding water. File down any sharp edges to make sure it’s all smooth. Use non-toxic aquarium silicone like this one and let it cure for 7-10 days before adding water.
#5: Mix of substrates
You can also mix two types of substrates in your axolotl’s enclosure. For example, you can have a thin layer of fine sand and then place large rocks on top of it. Or, you can have tile + sand.
This will prevent your axolotls from ingesting any sand. Sand will also prevent any waste from being trapped between large rocks. If you use live plants in the tank, it might also help keep plants in place (as axolotls often uproot plants in a tank).
However, cleanup might be much harder, and you will need to clean the sand on the bottom. You will sometimes also need to stir up the substrate to prevent bacteria from accumulating as well.
Bad substrate option for an axolotl
#1: Crushed rock, chippings, broken shells or other sharp substrate
Make sure to never use any sharp substrate in your axolotl’s cage. Axolotl’s skin is very delicate, and can get easily damaged or scratched when they roam the cage.
Never use any crushed rock, quartz, construction sand, chippings, broken shells, coral sand, colored rocks or sand in an axolotl enclosure. All of those can seriously damage your axolotl’s skin and internal organs if ingested.
#2: Small rocks/gravel/pebbles
Once again, you must not use any small rocks or gravel in an axolotl cage. Axolotls suck in their food and will swallow rocks, leading to impaction.
Rocks and gravel are not good to be used as a substrate in general, but if you decide to go with this option, always choose large, smooth, round-edged rocks. Any rocks/pebbles must be 3 times larger than axolotl’s head, so that it can’t swallow them.
#3: Sharp, contaminated or coarse sand
If you choose to use sand in an axolotl tank, please use fine pre-washed sand. Never use construction sand (sharp and might be contaminated), or other types or coarse sand. Play sand is permitted however.
#4: Glass stones/beads/marbles
Glass stones or marbles are aesthetically pleasing, but you must not use them for an axolotl cage. They are not appropriate for an axolotl tank because axolotls can easily swallow them, and it will cause impaction.
#5: Reptile moss mat or fake grass mat
Some axolotl owners are using reptile moss mats for axolotl cages. However, most mats are not truly for full water submersion. They are rather designed for dry, or moist and damp conditions.
Keeping a reptile moss mat in an axolotl’s tank all the time might cause it to leech toxic substances and also affect your water quality and harm your pet. While fully submersible grass mats are available, please be cautious if choosing this as a substrate.