Swimming does not mean stress. Swimming means swimming - some axies are just more active than others. Unless it's frantic darting about, in that could it mean your axie is stressed.
You need to add more water - the water should be deeper than your axies are long. So if you axies are 4" the water should be at least 6" deep. And your filters can't be running at anything like an efficient rate unless they are submerged.
I would get a permanent tank set up ASAP. You don't need an airstone, but some axies like to play in/snap at the bubbles.
Axies like to hide under things, climb up or onto things, sit in things - plastic plants are great for them, and Iwould look at another hide too. Real plants can sometimes be hard to maintain because of the lack of light in an average axie tank, but there is a list on here somewhere of plants that are suitable - check in the 'tanks etc' section.