This fish always mistaken by most people as freshwater ray, even LFS!
Actually they are hillstream loach from family Balitoridae . THe first pic is Chinese hillstream loach (Beaufortia kweichowensis ). Second pic not sure!
In the wild, hillstream loach live among the rocks in fast flowing stream. So, good water movement along with hiding and resting places created with plants, rocks, and driftwood in will be appreciated. They are omnivorous, but they prefer graze on algae!