Since your tank is new, it's not fully cycled.
http://www.kokosgoldfish.com/care.html
http://www.goldfishparadise.com/
That pleco will not attack your goldfish until it gets much bigger. The type of goldfish that you are keeping are common comets. They can live up to 20 years if you keep them properly.
Don't over feed and do 20% water changes every week.