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Swordtail Sex-Change ?!?!?!?!?!
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General message area: Swordtail Sex-Change ?!?!?!?!?!
January 22, 2002 - 01:17 am
I have heard form several sources that female Swordtails
can turn into males (I think this is supposed to happen
when there aren't enough males around). I'm
not entirely sure how true this is but when I was in the
LFS today I saw three female green swordtails - I would
have bought them but when I looked closely at one of them
her anal fin wasn't the normal 'fan' shape,
it seemed to be a bit elongated and narrowed when compared
to the other females (but it didn't quite look like
a males gonopodium either). And then I looked at her
tail and it seemed to have a small split in the bottom of
it as though a 'sword' was going to start growing
form it! I know it wasn't just a juvenille male because
it was the size of a fully grown female. I wish you guys
could see it. It doesn't seem to be a male or a female
- something in between! Can anyone shed some light on this,
January 22, 2002 - 07:24 am
I don't really remember if swords are sexually diamorphic,
but I think some African Cichlid are. I'll have to find
where I read that as I think sometimes it's a little
controversial and just a miss on determining the correct
sex in the first place.
January 22, 2002 - 12:48 pm
Sierra, what happened is the that female is very old. Old
female swordtails will develop a gonpodium. Luckily they
cannot breed though they will try. They also develop a small
January 22, 2002 - 04:59 pm
Old? How old? Will she soon be going to 'the big aquarium
in the sky'? I didn't want a male but I don't
really want an old fish either. But I might just get her
anyway because she looked so nice and I'll get her two
friends as well She needs a nice place to spend the rest
of her days and someone who doesn't mind that she's
Hey Joyce, I reckon sexual diamorphism must a 'survival
of the species' technique, right? Can males turn into
January 23, 2002 - 07:08 am
I'll try and look around for the article when I get
some time. It was either in one of my books or A fish and
I don't think it works the other way around. By the
way most livebearers don't live all that long anyways.
Not sure on the swords, but I know I read guppy only live
1-2 years. I think it's probably because they are so
prolific and also livebearing fish.
January 23, 2002 - 08:06 am
Found a marine site with the answer to your question. Most
commonly it's female to male ie some wrasse, but the
clownfish can go from male to female. I think these sex
changes may be more commonly found in marine fish as I also
got a hit on tuna!
January 23, 2002 - 04:05 pm
She won't be going to the 'Aquarium in the sky'for
a couple of years in optimum conditions. She can't mat
January 23, 2002 - 05:09 pm
I'll get her and her friends today! I hope they're
still at the LFS though.
January 23, 2002 - 09:57 pm
Hey, let me clear up some confusion here. Swordtails do
NOT change sex. There are hermaphrodite fish (joyce,
I think you meant this, that they have both male and female
genitalia? sexual dimorphism just means f & m's
look different, which swordtails are)... and there are
fish with potential to really change internal sex organs
given environmental stimulus.
HOWEVER, this swordtail issue is different. This was confusing
to breeders in the early 70's, but I think the consensus
nowadays is largely that they don't actually change
sex... they were merely males all along internally, but
"late bloomers" (you'll notice that all
fry have female-looking anal fins instead of gonopodium
when they are born). Not all swordtails mature at the
same rate, and some will develope their actual swords even
later, sometimes as late as a year old!
January 23, 2002 - 09:59 pm
I reread my msg and found it a bit confusing itself... just
to clarify, when I said there ARE hermaphrodite, I meant
species other than the swordtail... usually rare marine
January 24, 2002 - 07:06 am
Pandora I also read that with swords it was mistaken identity
due to the development of a gonpodium.I have read though
of a few fish that are sexually dimorphic and as I noted
most of these are marine fish and it isn't very common
just a few species. The marine site only listed wrasse and
January 24, 2002 - 07:08 am
Pandora you can clarify the terms though I got my hit on
the changing sex when I did the search on sexual dimorphism?
January 24, 2002 - 07:14 am
"Much like their amazing ability for changing colors,
the parrot fish presents a very inter-changeable mating
pattern. In many species the female will become a male during
the mating season. Males that are born into the species
remain male and tend to surround themselves with many females
once they have established a nesting site or territory"
Here is another one that will change sex(whatever it's
January 24, 2002 - 07:37 am
Interesting site about many marine reef fish changing sex.
Thought you might be interested Pandora if you are starting
salt water tanks.
January 24, 2002 - 11:36 am
Here's a few definitions for you guys (probably
look in Webster's for the official one, these are off
the top of my head and might not be complete):
Hermaphrodite--An organism that possesses both male and
female genitalia within the same body
Sexual Dimorphism--Consistent differences between the male
and female genders of the same species beyond just basic
anatomical genital differences (Examples of animals
showing strong sexual dimorphism: peacocks, guppies, swordtails
because of the sword... on the other hand, fish that are
hard to sex, such as many tetras, show little sexual dimorphism.
It is a continuum, and some would argue humans fall in the
middle of this spectrum).
Protogyny--An organism that starts out female and turns
into a male
Protandry--Other way around
I did a little bit of reading on this after the post, joyce,
and I had underestimated how many fish really do change
their sex throughout their life! I think actually it's
the majority of reef fish that do change sex, rather than
the minority, which is very interesting. I think it has
to do with the difficulty of finding a mate in a reef ecosystem
where territories are pretty small for individual fish,
and many don't school in the shallower regions. Just
FYI, this is really interesting, but I've also read
articles about Pacific Salmon changing sex due to environmental
stimuli like seasonal rainfall and pollution!
Anyway, interesting stuff... really makes you think about
how our rigid definitions of male and female for humans
are not universal in the animal world. There are interesting
stories of a desert lizard species which are all female
and usually gives birth to clones... they only breed sexually
with males of other species. There are also hermaphrodite
animals and plants that can fertilize themselves. Or how
about this... I used to work in an entomology lab with aphids...
they can choose to either breed sexually, or reproduce asexually,
giving birth to clones, called parthenogenesis. The interesting
part is, a big female aphid can give birth to young that
are already pregnant... in effect giving birth to both her
children and grandchildren at the same time!
Well, just some random trivia I found really neat...
Ain't Nature wild? =)
January 24, 2002 - 07:16 pm
I wonder how many reef fish change sex in the aquarium?
I wonder if successive generations loose this capablity?
I'm not sure a lot of the reef fish can even be tank
bred. Guess I'll have to keep reading the saltwater
articles in A fish magazine. Those lizards sound really
bizarre! Anyways thanks much for the term updates it helped
get things straight!
January 26, 2002 - 10:23 am
Sure thing, joyce. I don't know about whether the reef
fish would ever change sex in captivity, it would be interesting
to research it! To my knowledge, the ones I hear of are
all close to impossible to breed, actually close to impossible
to sex, in captivity (one of the reasons they are so
expensive and there's such a controversy in the hobby
about the destruction of the natural reef by this hobby).
They probably need really exacting requirements that we
aren't able to provide in an aquarium setting, although
of course I'm new to reef tanks just like you.
Hey, and I got my first fish for that tank too, joyce...
my first SW fish... a yellow tang! He's doing great
so far, swimming around and picking stuff off the Fiji live
rock. I also bought this guy's half-dead open brain
coral, and I feel like I got ripped off already (he
was selling everything for a bit much for a tank that was
falling apart, IMO, and I wanted to get something just to
get out of there and not have come for nothing. The brain
coral is showing it's skeleton on one side, but the
live side still has color, do you think I will be able to
nurse it back to health if I have good lights?
January 26, 2002 - 12:36 pm
I know from others comments that lights are really important
for coral growth.I guess if you do have some color and part
of it is living it's certainly worth a try. That marine
stuff costs so much in the first place I think whatever
you can save is great! BTW those tangs are just gorgeous.
I've seen them many times in a couple of Marine shops
around here. What did you use for substrate? Do you have
any of those shrimp?
January 27, 2002 - 01:34 am
Hi! I got the swordtails, including the 'shemale'.
The fish is just like I explained earlier and I don't
think I have made a mistake. The fish is as large as the
other females (perhaps slightly larger). Male swords
are usually smaller the female swords, aren't they?
Tha bottom part of the caudal fin is thickened and extenteds
aqbout 1/8 in. beyond the rest of the tail. The 'gonopodium'
isn't quite right because it is not carried close to
the body - it just hangs there and there's still a bit
of female 'fan-shaped' anal fin with it. So if its
not a sex-changer then I don't know what it is. Maybe
it was born somewhere in between? I don't mind though
because its a bueatiful fish
January 27, 2002 - 10:15 am
Sierra, as I explained swordtails are not true "sex-changers",
but what you're seeing is not uncommon either. A lot
of breeders have noted this before. There was a lot of debate
in the 70's about it, but mostly it's resolved now...
it's a "he" and he's probably just a late
bloomer. Give him some time and he still has a chance at
developing into a "proper-looking" male.
January 29, 2002 - 02:44 am
Oh. I didn't really want a male swordtail. But I've
got him now so I can't do anything about it. 'He'
is more aggressive tham the other two swords, which are
definately females. I got a blue gourami today and the 'male'
sword was giving it a bit of a hard time. He just kept following
it and nibbling its tail. So I trapped him in a clear plastic
take-away food container and weighted it down so that it
sits on a rock in the middle of the aquarium. He can still
see the other fish and they can see him - hopefully this
will be enough to cool him off and give the gourami a chance
to settle in and become more confident. It's weird because
I expected that if anyone would harrass the gourami it would
be my krib who chases everyone else away from her caves,
but she lets the gourami go inside the caves and explore!
Fish personalities are very interesting!
February 02, 2002 - 09:44 am
Yeah, they are interesting, aren't they =) Some
fish species are naturally aggressive, but then I've
found variation between individuals within the same species
as well... bettas and angelfish are a prime example of this.
Just a note on "trapping him" under a clear bowl,
however... this is late telling you now, but I hope you
removed the bowl and didn't keep him there for long.
That does not provide much water circulation if you pinned
it close to the gravel, and he could suffocate because of
poor gas exchange (it obviously won't be airtight
because it's open on the bottom, but the water won't
flow well through the gravel). I suggest that you buy
a fish divider next time if you have this problem again.
February 04, 2002 - 02:59 am
Don't worry, I only kept him in there over night and
when I let him out the next morning he was still causing
trouble so he has been exiled to the 10 gallon tank with
my zebra danios. I will put him back in the main tank when
I have cured an ICH outbreak in it He was probably lucky
I moved him out, otherwise he would have gotten it too.
Also, I had the the 'takeaway' container up the
right way with the lid on and before I put him in it I punched
a whole lot of holes in it for water circulation. The container
was sitting on a rock near the filter outflow so I figured
he would be OK for a short while. I now have a 'net
breeder' and one of those plastic convertable breeding
traps so if I have any more trouble-makers in the future
I will put them in one of those. Thanx for your help.
February 05, 2002 - 12:41 am
Oh that's good. How's the battle going now? You
know, your ich problem may not be totally unrelated... when
fish are stressed, they are more susceptible to such things,
and the bullying can take it's toll after a while. I
hope you figure out some way out of both the disease and
the incompatibility issues!
February 05, 2002 - 09:14 pm
Well, I've only been treating for two days and the cysts
are already gone (but don't worry, I won't stop
treating for at least a week). The fish are a lot happier
and their fins aren't clamped anymore. They've also
stopped hiding in the rock caves as well. They're still
eating and I've been giving them little bits of food
2-3 times a day. I know some people say its not good to
feed fish while they're sick. But I think that if the
fish are hungry then its a good sign and there's no
need to deprive them of food if they want it.
I think it was a combination of things that brought on the
* The bullying from the male sword (mostly directed
at the gourami and the other female swords) and then
from the gourami (directed towards everyone) after
I removed the sword *sigh and roll of the eyes*
My krib can give the other fish a hard time (even though
she's the smallest fish in the tank) but I think
she's just territorial and doesn't want the other
fish in 'her' caves.
* I dropped the temp. in the tank by about 4-5*F
over several days to try and reduce aggression (sort
of worked). But this may have made the fish more susceptable
to disease (esp. the new mollies).
*I introduced a new fish (unquarantined)from
a bad petshop the week before.
* I got the mollies the day before I realised the fish
had ich. So these new additions (and their bossy behaviour)
might have stessed the fish some more.
Plus I think maybe it was 'my time' to have something
go wrong. I only started to keep fish four months ago but
I have had to major problems (apart from my first fighter
jumping out of his bowl - he's fine now) and no