Just for the history, to complete this thread about bristlenoses and stingrays, I had left a pair of bristlenose in my tank. The male was missing for 2 days I couldn't spot him nowhere. I noticed that he went missing after a pellet feeding. So today was my next pellet feeding, and decided to monitor the situation. The stingray caught the female in front of my eyes. While the bristlenose was super careful all the time about the stingray, in feeding time she was just too careless. Of course I was just next to the tank, so I took the ray off, so pleco escaped and removed from the tank! So this thread closes with a missing bristlenose and a no no from my side for rays and bristlenoses.