The first thing to remember when picking axolotl substrate is no pebbles, no gravel, and no small stones. This is the golden rule. The way that axolotls feed is by suctioning in their food, and this means anything nearby is also at risk of getting sucked in too. As we have previously mentioned, axolotls are also prone to taste-testing anything that they will fit in their mouths, and these small rocks and gravel run the risk of causing a potentially fatal impaction or blockage. Below you can see an image of an axolotl that ingested stones that were in its tank.
Sand
Sand is an excellent option for your axolotl tank. It is aesthetically pleasing while also being able to pass through your axolotl’s digestive system easily if accidentally ingested. This is an excellent option if you plan on having live plants in your aquarium, as you can just have a dirt layer underneath. In addition, waste sits on top of sand for easy visibility when cleaning
Sand comes in various types and levels of coarseness, and you want to make sure that your sand is fine rather than gravelly. Gravelly sands can be sharp, almost like tiny splinters, so you want to make sure you pick carefully. As a guideline, your sand should be smooth and smaller than 1 mm.
Sand should never be layered more than 1-2 inches, and should be stirred up weekly to make sure there is no buildup of gas or anaerobic bacteria (bacteria that grows in oxygen-free environments).
Last note, make sure to to rinse the sand well before using it in your tank, you want to make sure the water is running clear by the time you’re done.
Barebottom Tank
This style of tank goes for minimal aesthetic effect, but extreme ease for maintenance and cleaning. As with sand, waste sits on top to be easily suctioned out. If you go with this style, you’ll have to pot any live plants you decide to add your aquarium. Additionally, some axolotl keeps have reported that their axolotls have a hard time gripping glass surfaces to move around, which can make them stressed. You’re going to want to have a few items in the tank for them to get traction on when they move around.
Tiles
Ceramic tiles are also a good option, coming in many colors and being easy to clean. The only stipulation here is you’re going to want to use unglazed/unfinished tiles, as some glazes contain metal salts which can leach into the water over time. As with a bare bottomed tank, if you plant anything in the pot you’re going to need to pot it.
Slate tile is also an option. If you take your tank or its exact measurements to a home improvement store, they can cut you a piece of slate the right size for the bottom of your tank. If you decide to go with slate tiles, you can refer here for a guide on how to determine if a slate tile is aquarium-suitable.
Large River Stones
Some axelotol owners decide to go with large river stones (“large” being defined as bigger than your axelotol’s head so there is no risk of swallowing). These are an aesthetically pleasing option, and can work if you decide to have a layer of soil underneath for tank plants. However, it is extremely easy for food and waste to get caught under or in between stones, out of sight. That makes this type of substrate exceedingly difficult to clean in comparison to others.
