Yes, sometimes plecos are in a light color...mostly due to lighter gravel. They can vary from a white-grayish color to a dark blueish-black with white.Is this a common pleco when they are juvenile?
http://www.petsolutions.com/C/Live-Freshwater-Fish-Catfish/I/Common-Plecostomus.aspx
The pleco in this picture is not a sailfin...it is a common. Sailfins are orange-black pattern. Here's some pictures of SailfinsI get confuse when I see these sailfin pleco at the local fish store mix in the same tank together.
http://www.liveaquaria.com/product/prod_display.cfm?c=830+837+1021&pcatid=1021
Yes, commons can get up to 24 inches but mostly stop around 12-18 inches. Sailfins can get up to 20 inches. Their fin gets larger(hence sailfin). Adonis can get over 30 inches.Is there any size difference when they are fully grown?
I was looking to get the Adonis Pleco but there aren't any in stock around this season. I think i'm better off with the common pleco