Are they really active cories? I introduce a pair into their own tank today. One stay near the back and the other is near the front. They are moving up and down side of the tank non stop.
There doesn't seem to be a lot of information on this cory.
One of the fowleri I got has a black bloch on the dorsal fin, while the other doesn't.
The only real suggestion I can make would be to change the gravel for fine smooth grained sand, they will be far happier sifting through the sand that trying to get their snouts under the gravel.