How to sex puffers (Arothron sp.)

[schlecht13]

Hello again all...

So you would think that studying marine biology would be able to find this answer somewhere...well needless to say I can't! I have dissected several of the Arothron genus and studied external characteristics through well preserved and live animals. I even saw two puffers in the Carribean (although it was hard to tell - they may have just been interested in each other - two Diodon Holacanthus - swimming round and round up and down...never saw any eggs/sperm - so honestly who knows)...either way till Sunday I still can't find much - externally on live animals....anybody know? I remember seeing one individual saying its not possible - externally in another post I had (can't find it right now so I apologize!)....

[SpockthePuffer]

I think the only puffers we can tell the sex of are dwarf puffers and one other one I can't remember...

[Jase]

you can sex red eyes I believe...

[yunachin]

Irrubesco's
Baileyi's
Dwarfs

That is all I know of currently.

[spoot]

...well needless to say I can't! I have dissected several of the Arothron genus and studied external characteristics through well preserved and live animals...

shouldn't you be able to tell after you dissect them? Not much of a biologist, but the different sexes should have different reproductive organs right?

[Pufferpunk]

If you can't sex them during dissection, then I don't know of any other way.

[Corvus]

@schlecht: Check Thresher: Reproduction in reef fishes. He at least describes successful mating of Diodontids in an aquarium as far as I remember. Some puffers can be sexed, but to my knowledge Arothron spp. are not among them. I think there might be some older literature (e.g. Abe, Uno, probably from the 1950s) with more information, they will certainly be in the references of Thresher. Those should be read, too, if you haven't already.

@Yunachin: I don't know for sure if M. baileyi can be sexed. Those skin filaments at least are no useable character. I believe this is a "hobby myth", just like some people say they can sex Dragon morays by color. It gets told on and on until it is accepted as fact... but in fact this was never prooven, instead research was ignored.

@spoot: I believe he tries to find external characters that correlate with the different reproductive organs, so we can sex the puffer without cutting it up.

[schlecht13]

I probably should have been more clear You can most definitely determine sex my dissection and I have done so succesfully with A. Hispidus and A. Mappa. I have dissected (2) of each, one of the hispidus was clearly female and the other male. Both Mappas turned out to be female.

However when I completed the dissections and then reverted to external characteristics, they looked almost identical. What I am looking for (I suppose) would probably be an enlargment of the openings in the fish before or during mating (which has not occured to my knowledge in captivity simply due most likely to the fact that most literature point to Arothrons being openwater spawners whose eggs remain in the planktonic layers for a rather long period of time...

[Jase]

where were you dissecting these puffers?

[spoot]

I probably should have been more clear You can most definitely determine sex my dissection and I have done so succesfully with A. Hispidus and A. Mappa. I have dissected (2) of each, one of the hispidus was clearly female and the other male. Both Mappas turned out to be female.

However when I completed the dissections and then reverted to external characteristics, they looked almost identical. What I am looking for (I suppose) would probably be an enlargment of the openings in the fish before or during mating (which has not occured to my knowledge in captivity simply due most likely to the fact that most literature point to Arothrons being openwater spawners whose eggs remain in the planktonic layers for a rather long period of time...

If no external differences can be found, I think the best way to sex a live puffer would be to sedate it and use ultrasound. For breeding non sexually dimorphic puffers, this may be crucial.

[marfisa]

Wouldn't another way to sex puffers be to take a skin sample from a rubbing of the skin or maybe a tiny, tiny clip off a fin and do a DNA analysis?

I remember in high school biology we did a thing where we swabbed the inside of our cheeks and then somehow ended up with those dark stripes in gel. Or does that method not show gender?

If it does show gender, maybe someone could even convince a local high school science class to do that as a project...

[schlecht13]

I like these ideas...mild sedation and ultrasound may work - problem here is sex organs are somewhat difficult to tell apart to begin with unless female has eggs present - I like it though. DNA analysis is very good and I do have access to be able to do this on a limited basis - problem would be cost/time. Thanks to all so far - I really like these ideas and this conversation!

[Nick]

Marfisa, the DNA technique you're talking about is PCR, it's awesome because it replicates a small sample of DNA so you need very very little to start with. It's probably MUCH more reliable than ultrasound, but you'd have to know what you're looking for.

[schlecht13]

I had thought about PCR and even almost mentioned it - thats funny you did However as you stated are are correct, I would have to know what to look for - would prove to be rather difficult unless this has already been done...

I used to utilize several genetic techniques in grad school including PCR and could probably utilize the equipment if needed. Just need to find the template

[marfisa]

Maybe someone has? Could someone on the GSP genome project help if you contacted them? I think at least one type of marine puffer has been researched too.