22 degrees is a wee bit high for them, but seeing as you are in australia i think your problems are just starting lol. you can try a fan faced down at the water surface or ice bottles used in rotation to lower it more if the fan doesnt help, but do be careful axies prefer warmer water the dramatic temperature fluctuations all the time. if you have the money invest in a tank cooler.
what are your water parameters? is your tank cycled?
sometimes they float when theyve gulped in a bit of air and can float for a couple of hours at the most probably, until they let it out but continuous floating can be a sign of underlying problems