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All fish reproduce sexually. In sexual reproduction, a sperm unites with an egg in a process called fertilization. The fertilized egg develops into a new individual. Males produce sperm and females produce eggs in almost all fish species. But in a few species, the same individual produces both sperm and eggs. In many species, fish change sex during their lifetime. Fish born as males may later become females, and fish born as females may later become males."
From World Book Online Americas Edition
http://www.sportsmanschoice.com/A%20Note%20Worth%20Reading/fish.htm
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[FONT=Verdana,Arial,Helvetica]3.[/FONT] [FONT=Verdana,Arial,Helvetica]Plastic Sex[/FONT] [FONT=Verdana,Arial,Helvetica]When, why and how fishes change sex as adults, with some examples from cichlid fishes.[/FONT]
http://ib.berkeley.edu/labs/barlow/book.html
George Barlow's book on cichlid fishes and their evolution is a delight to read. Barlow, is Professor Emeritus in the Dept. of Integrative Biology at the Univ. of California in Berkeley. He makes no bones about tailoring the book for a lay audience, although it contains a wealth of easily readable scientific data.
From Barlows Book Explaining Plastic Sex
Cichlid success may
also be associated with the ability of an individual
to change its sex in certain conditions,
a process perhaps best known
from examples of tropical reef fishes. In
the chapter titled “Plastic Sex,” cichlids
that are capable of changing their sex,
including an African tilapia and an Asian
chromide, are described, as are the effects
of pH and water temperature on
sex ratios. The concept of sexual plasticity
may be new to some readers. It does,
however, help explain why the two female
Midas cichlids in your tank are suddenly
rearing a clutch of fry in the absence
of a known producer of sperm.
So now
excuzzzeme, no need to be arrogant, finding information online is nothing but a matter of taking the time to find the actual information about it.