Woke up this morning to find my Valentini puffer that I’ve had for around 2 months rather motionless sitting around but breathing heavily. Usually he’s awake and swimming around the tank at this point but just keeps landing on the rock. I tried to feed him which he’d usually go mad for but he just stayed put. Hasn’t moved for a few hours now but is still breathing heavily and moving his fins. Water parameters are all good, no odd behaviour in any fish, coral or inverts, seems fat and fully coloured with no signs of infection. I’ve done a water change and I’m continuing to monitor his behaviour. My only clue is that he puffed up very randomly and brifley yesterday but he seemed fine after. Any ideas?