It's all a matter of becoming informed. Knowledge is power. If you want the best info, the scientific name is essential. In some cases a fish can have half a dozen different English names, in different countries. I've seen some advice go seriously crazy when several people gave good answers but about totally different fish with the same marketing name. If you think the trade is shady about disease management (if you do, you're right), watch how they change the names on some fish to make them seem 'new'. Your Cory has been sold as salt and pepper Cory, Pepper Cory, Mottled Cory, Blue Mottled Cory...
The photo's grainy, and it could be aeneus. But the big patch on the back of the head would be normal for paleatus and not normal for aeneus....