Hi Keisha.
I have an idea that maybe there are some other underlying problems here.
What do you feed it? Veggies? Do you feed food specifically for it at every meal? Do you stick around to make sure it gets it?
Is there any driftwood available for it? (some say it's necessary)
Are there large enough hiding places for it where goldies wont be able to disturb it?
Does it have a regular lighting schedule?
Are the goldfish that were nibbled on bottom sitters? Are they very round or plump to where they have a hard time swimming?
I think you can see where I'm going with this.
A malnourished pleco, no matter what variety, will take advantage of a sick or slow swimming goldfish to get nourishment.One of the best way to find out if your pleco is well fed or not is to look at their heads jus behind their eyes. There are two ridges of bone there that has fat or muscle in between them. If that area seems to sink in a bit, your pleco needs more food. If it is a very even roundedness all around that area, it is getting the nutrition it needs.
What does yours look like?
Post back soon.