I bought a bristlenose Pleco three days ago. I put it in and it seemed fine, just a bit shy. On the first day it wasn’t eating, but it would move around the tank and suction into different walls. That night I measure the pH and it was a bit high, 7.4. I put pH down in it and measure the next day and it had gone quite a lot too low, 6.6. That afternoon I noticed my Pleco wasn’t moving too much, wasn’t eating, and was lying near the bottom of the tank and breathing really hard. I thought the low ph might be affecting it so I got it back up to 6.8-7. It’s still doing that this afternoon, and appears to be having trouble suctioning to the side of the tank, and it won’t eat any of the wafers I give it. I have 5 neon tetras and 5 diamond tetras in the same tank, who seem completely normal. It’s a 65L tank and has 0 ammonia. Apart from potentially increasing oxygen by a tiny bit, I don’t know what to do. Thanks!