Trey is Khmer for fish, I think. Kantrop is a citrus-type fruit and leaf used in Cambodian cuisine. The fishbase photos show the fruit to have the same colour as the trey fish. I found mention of it on mmm-yoso!!!:
He spelled it Kantrop*. I found several citations of it, in English it’s called Wampee, or Chinese clausena. It is the leaf of a certain type of citrus fruit tree. In Vietnam it’s called Hồng bì, I had never had anything like it before. We even saw the trees growing on the trail up Kbal Spean.