I got my first clownfish pair, unfortunately one of them (the runt) had white stringy poop and his swim bladder was messed up. I caught it too late though and he passed away today. Many tears were shed. This other one seems totally fine, but recently started swimming all along the tank walls. Is this to be expected? Or should I take it back and look at water I’m slightly post cycle with 0 ammonia 0nitrite and some nitrates but there was a small spike when the other died.