Pleco acting weird and swimming upside down

Question

I have a 25-30 gallon tank that originally had one suckerfish in it but when we broke down a 10 gallon tank we had to add the suckerfish from that tank into mine as well. This one is a lot smaller than the one that was in the 25 gallon and it was black. they got along for the most part and didn't seem to bother each other but lately the black one has been acting... eradic. It swims in backward loops quite often and then will float upside down at the surface of the tank but if you touch it it'll just swim away and sit on the bottom or side of the tank like normal.

everyone keeps saying it's dying but I don't think that's what it is. Does anyone know what might cause it to act like this?

Answer 1

Is there enough food for him to eat? If your one pleco was keeping algae in check and you put in a new guy... maybe hes hungry. Do you feed them algae wafers?

Answer 2

Sometimes plecos just act like that, because I had one that lived for about three years and for about 6 months, he would always float upside down on the top of the wATER.  I don't really know if they are wanting air, but mine lived long after he did that so it's normal.