Those look like bronze Cory cats to me.Here is the picture of my Cories, which I believe are rust Cories. View attachment 110409
Your GH is good for these little guys. I do need to suggest you do a substrate change - while colorful gravel may look cool, it is no good for Corydoras. They are naturally scavengers, and need sand. Gravel can damage their barbels, leading to infection.
(they also need to be in groups of 6 or more.)