Thanks for the help.
Rayman
The ray was imported a month ago and bought buy another hobbyist and - according to the him -, it has been eating earthworms (check the 2nd pic).
Kevin
It will not be possible to do what you are suggesting (I just spoke with the owner). You have to understand that Portugal is a very small market and even smaller for stingrays (there should be less than 20 in the entire country, mostly motoros), so its a selller market: when one pops by, you take it or leave it...
Anyway, with the dent and not knowing how big it will be and how it will look... I´ll probably pass by