Tanks for axolotls don't need to be half filled, or quarter filled. Reducing the volume of water in your tank only allows ammonia and nitrites to build faster. So you might have a 10 gallon tank, but if there was only 3-4 inches of water there, then it will be no where near 10 gallons. At that depth it would also be very difficult to get a filter to work properly, which is essential for axolotls as they produce a lot of waste.
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