Hi Diann,
That's right, tropical fish can't be kept with axolotls - axolotls require temperatures less than 21°C, so either the fish or the axolotls (which aren't fish, by the way
) will suffer in a community tank. I keep guppies and platies in my aquarium with the axolotls - but they are intended as food. As long as the axolotl does not have any open wounds, the fish will not nibble on them or their gills, and they tolerate the low water temps fine.
How long is a 220l tank? It's the floor dimensions that matter most, as that's where axolotls spend most of their time.
Adding lots of retreats, places to hide, will help deter biting. Axolotls don't fight; rather, they are very shortsighted and hunt by smell/movement and so snap at anything that moves (particularly younger ones), and in this way they can accidentally bite each other.
Do be sure to read up more before getting your new pets:
http://www.axolotl.org/
Good luck to you,
-Eva