What would effect the fish if given foods other than meats? I can't even train my rtc to take other than mackerel.
Jibran is simply mimicking the RTC diet in the wild, where they take fallen fruit along with almost anything else edible they come across - slow-moving (or not moving) fish, crustaceans, mollusks, amphibians, reptiles, mammals, birds, etc. They are not known to be herbivores IIRC so they won't glaze algae or other water plants. But fallen fruit they are known to take from their stomach dissections. As well as turtles and an occasional duck.
IME, almost all RTCs will take anything you give them after a short fast or even right off the bat. I have had one exception for a couple of years now who mostly refuses pellets and only wants fish, fish, fish.