Sex changing guppies

first want to state im not an expert in fact im a "dumb"student trying to pass semster....of note though in our zoology textbook there is a section on gender reversal....and it states that in the fishy world gender reversal is very common,more so than evenmost scientist think....BUT transformation in both directions male 2 female (protandry) and female 2 male (progyny) is highly rare and is typically specie dependent on direction....this is called sequential hermaphrodism ...also of note is it is being discovered more common than previously though in amphibians gastropods and plants...

again not my knowledge just extracted from textbook.....