Is this normal pleco behavior?

[JoCinWB]

I moved my common pleco to a larger tank four weeks ago. He was alone before for a long time. He occasionally did some fast turning in the past but not a lot of flopping around. Now he's smacking the lid of the tank many times a day. He never did this before. 

The other tank had a black hood, this has a glass flat lid. Our water is very soft (I will address that shortly) but the other numbers are good. He sticks to the glass sometimes, as usual, but also does that leap face-first straight up. He used to come to the surface when I dropped in some flakes, but no longer does this. He sometimes grabbed his algae wafers and carried them around eating them, but does not do this now. I add a pinch of flake in the morning and give him his wafer at night. His companions now are three mollies.

Is this normal? Was his generally placid behavior in the past NOT normal? I've had this guy for maybe eight years. I'm concerned. Also on edge bc his leaping is startling me.

[Colu]

How big is your tank what fish do you have with the Pleco what are your water parameters ammonia nitrite etc

Edited April 16, 2021 by Colu

[JoCinWB]

The numbers are good, other than soft water. 0 nitrites, 40 nitrates, pH between 6.5 and 7

Just the 3 mollies I mentioned

 

[Colu]

What size is your tank as common pleco grow up 2ft if the tank does not have a big enough foot print when they get startled they can swim in to things injuring themselves 

[JoCinWB]

Well then I guess he's afraid of the mollies. I thought he was ignoring them. Thanks.

[Yanni]

I don't think that its the pleco being scared of the mollies. What is the size of the tank? A small tank would most likely be the cause. 

[JoCinWB]

It's 20g, but why would this only start when he moved to a larger tank? 

[Colu]

How big is your common pleco