I don't have much to add to what was already said. But definitely keep them in a species only tank, only use feeder guppies or something as a treat. The reason is because 1) they will eat the fish, and 2) the fish will nip at the axie gills. Their staple diet is earthworms, if they are small when you buy them you will have to cut the worms so they are no bigger than their heads. They can also eat bloodworms and brine shrimp, but worms should be their everyday meal. They grow very fast! Mine doubled in size in two weeks. They went from 2" to 4" in no time! They also have huge poops lol, you'll have to clean them out with a turkey Baster (or something like that) lol. Or maybe my water siphon just sucks, but I have to use a turkey Baster! They need cold water, no temps over 72F. They're not any more maintenance to take care of then fish... Same thing, test for ammonia, nitrite & nitrate. Because they are sensitive they should not be added to an uncycled tank. If you have such few options at your pet store, try looking online for axies, there is probably a breeder that can ship you the other color types. I have a golden albino (named Cersei), dark Melanoid (named Jon Snow), leucistic (named Arya) and a wild type (named Daenerys). They are 13 weeks old right now and 4.5" long. My small guy, Daenerys is only 4". They live in a 45G Bowfront. I keep the water up to the top, some people only fill theirs halfway. My guys have no problems swimming up for air and they love the extra swimming area. So it's up to you how full you want to fill your tank. No rocks. No sand until axies are at least 5" long. When you add sand make sure it is smooth and max 1mm grain size. This will make it easier for them to pass when they suck up sand while eating. To help stop this, I just got a reptile feeding dish and put their food in there. It also makes it easier to clean uneaten food. They don't like bright lights, give them caves and hides. Floating plants are good to help block the light.
Attached are pictures of my guys! Old and new pics, so you can see how much they have grown! They were 2" when I first got them.