Anthia acting strange

[Nemo1]

Noticed my Anthia heavy breathing and resting on rocks in a crevice, whqt could be wrong? No sudden changes have taken place and he’s not being bullied by anyone, I fed the tank to see if he ate which he did but goes back into the rock work

ammonia 0
Nitrate 0.25
Phosphate 0.03
Calcium 500
Alk 9
Salinity 1.025

 

[Big G]

Heavy breathing can caused by a few different things like parasites, ammonia, illness, stress, age. A freshwater dip would either confirm or eliminate parasites from the situation.

 

[Nemo1]

He has only been in the tank 2 weeks if that’s got anything to do with it but he’s been completely fine up until now
How would I do the freshwater dip?