I know this is an old thread and you probably got your pleco or decided against it by now. I have two frontosas and another large cichlid that has a big latin name (that I can't remember right now) . All are African cichlids and I have a pleco with them. They are in a 55 gallon tank, which I will upgrade when my frontosas get larger (they get to be 12 inches if they are males and 10 inches if they are females) Frontosas are very agressive so I have to make sure my pleco was at least the size of the largest Frontosa. The Frontosas and the Pleco have been together for over a year and the new guy has been there for a few weeks, all is well.

My advise is that a 10 gallon tank is pretty small, but if that is what you have then there is nothing you can do. However, you said you had a 35 gallon. I think you should get them in there asap and then get the pleco. Hope that helps.

PS. Don't ever believe what someone that works in a petstore tells you. Sometimes they mean well, but often don't give good advise.