Yes it is possible it is a heater burn spot (see my post above) and it is very evident that he is too crowded in that tank. When a tank is too small, health problems including stunting occur. Stunting will shorten his life considerably and may lead to secondary ailments as a result. This is a fish that should live about 20 years. I have one that is about 7 years old. The correct name of this fish is Pterygoplichthys Pardalis or P.disjunctivus depending on the pattern on his stomach. For more information on this fish go to: http://www.planetcatfish.com/catelog/_species.php?species_id=88