Pleco on his side not sucking

[Oreocupcake]

I recently got a pleco from a friend who had him for 4 yes and the first day he was fine. Now he is on his side occasionally moving but won't suck or go on the glass. He looks fine but his fins are fraying but no spots or discoloration. I don't want my fish to pick at him if he is sick. Thank you for the help

 

[dkpate]

Has your tank gone through the nitrogen cycle?

 

[Oreocupcake]

Yes it has

 

[dkpate]

Ok good.

Did you acclimate him before you put him in?