Thanks for your question.
The exact name of the fruit is not given. Was it an apple, an orange, a papaya, a kuquat, a promegranate? Nobody knows and it is irrelevant. It was called the "Fruit of the knowledge of good and evil". As soon as God gave a prohibition concerning that fruit it BECAME the fruit of the knowledge of good and evil whatever variety of fruit it actually was. It was Adam and Eve's reaction to the commandment that was important NOT the nature of the fruit itself.
I hope you have found this helpful.