They are not rare at all, look for Sequential or Spontaneous /Simultaneous
Hermaphroditic fish. Atlantic Hamlets can change their sex many times a day. There was a
lengthily article on them in American Scientist mg a few years back. This article also has
a discussion on Sequential Hermaphrodites, like clown fish.Other key words are
protogynous or protandrous

Warner, R. R. 1984. Mating behavior and hermaphroditism in coral reef fishes. American
Scientist, 72:128-136

http://www.fishid.com/learnctr/hamlet.htm

"1 .Sequential hermaphrodite: The organism is born as one sex and later changes into the
other sex.

a. Protandry: When the organism starts as a male, and changes sex to a female later in
life.

Example: The seabasses (Family Serranidae). These are a highly sought food fish complex
made up of primarily groupers. Since even a small male can produce more than enough sperm
to fertilize a huge number of eggs, while a female's egg output increases greatly with an
increase in size, this strategy makes sense for an organism (fish in general) where over
90% of the eggs laid will not result in a fish that reaches sexual maturity. It has been
shown that fishing pressure actually is causing a change in when the switch from male to
female occurs, since fishermen naturally prefer to catch the larger fish. The populations
are generally changing sex at a smaller size, due to artificial selection.

b. Protogyny: When the organism starts as a female, and changes sex to a male later in
life.

Example: Wrasses (Family Labridae) are reef fish that tend to have three distinct sexual
types. Small females, immature males and supermales. The small females and the immature
males have identical colorations. The supermale is usually brightly colored, and there is
only one in a given area of the reef. This supermale dominates the other wrasses of the
species, having the choice of females to mate with. When the supermale dies, the largest
wrasse in the area, male or female, becomes the new supermale.

2. Simultaneous hermaphrodite (or synchronous hermaphrodite): The organism has both male
and female sexual organs at the same time as an adult. Usually, self-fertilization does
not occur.

Example: Hamlets, which (unlike other fish) seem quite at ease mating in front of divers,
allowing observations in the wild to occur readily. They do not practice
self-fertilization, but when they find a mate, the pair takes turns between which one acts
as the male and which acts as the female through multiple matings, usually over the course
of several nights."
--
Boomer

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"Jaime R-S" wrote in message
. ..
: What he is looking for is rare and better not waste time looking for it. He
: is looking for a hermaphrodite species of fish that has both sexes at the
: same time. It can be found and, as it happens with humans, can be found but
: is not a trend.
:
: jrs
: "Don Geddis" wrote in message
: ...
: wrote on 1 Nov 2005 14:10:
: Are there such things as aquatic creatures that have the same sex? I
: am doing some research but don't know where to begin.
:
: Clownfish are neuter, and then later develop into males or females as
: adults
: depending on what is needed in the local community.
:
: I'm not sure if that's the kind of thing you were looking for or not, as
: your question is worded a bit oddly.
:
: -- Don
: __________________________________________________ _____________________________
: Don Geddis
: http://reef.geddis.org/
: If you ever feel like you're on the verge of a nervous breakdown, just
: follow
: these simple rules: First, calm down; second, come over and wash my car;
: third,
: shine all my shoes. There, isn't that better?
: -- Deep Thoughts, by Jack Handey
:
: