[plesner]

Just my 25c: My first thought as far as the source of the bacterial infection is concerned, was the red mosquito larvae. Many of them are not exactly clean and are btw. highly allergenic. By handling red mosquito larvae every now and then for about a decade, I became allergic to shrimps and other crustaceans as well as red mosquito larvae of course. Other people in the hobby have had similar experiences.

 

I’ve also heard of several people losing entire batches of fry, because at some point they began giving them red mosquito larvae as part of their diet.

[plesner]

@Matt said:
Any idea what these optimal conditions are Karsten?

Not really. Whenever I asked, I got some sort of vague answer. Constant access to food and lots of water changes. That’s not very informative to say the least.

[plesner]

@Matt said:
Yes, think I do. Let me check. Also have some other stuff that might be useful for you.

Thank you Matt. It’s very much appreciated.

 

plesner

[plesner]

Bojan Dolenc said 
Book: Genetics for Aquarists, Schroder – TFH

PDF: Sexual Behavior, Genes, and Evolution in Xiphophorus.

http://www.ikhebeenvraag.be/my-aquariumstorage/FSDocument/58/Rosenthal-85.pdf

> Genetica: Variability of genetic sex determination in poeciliid fishes. J.-N. Volff and M. Schartl
http://www.springerlink.com/content/u863176070811552/

Thanks again Bojan. I only seem to be able to find the 1976 edition for sale. Will that be ok, or should I wait until I find the 1991 edition available somewhere?

 

Oh, and does someone in here have access to the text from Genetica?

 

[plesner]

@Bojan Dolenc said:
Poeciliids present an amazing variety of mechanisms, which span from simple XX-XY or ZZ-ZW systems to polyfactorial sex determination. The gonosomes of poeciliids generally are homomorphic, but very early stages of sex chromosome differentiation have been occasionally detected in some species.

There are 2 types of males in the swordtails with polygenic autosomal sex determination mechanism: earyl males (“strong” males) and larger late males (“weak” males), which become sexually mature much more later.

Thanks Bojan. Would you happen to know of one or more good sources to read more about this topic?

[plesner]

@Matt said:
As far as I know there’s no scientific evidence to support this theory.

Where are you planning to publish Plesner?

I’m still only thinking about it. I’m considering one or more articles for a Danish site I use – Danish is my native language after all. As there are far more knowledgeable people in here, I thought I’d ask here.

[plesner]

I’ve never experienced an old female, which developed male characteristics being even interested in the ‘real’ females at all. Usually they die of old age 3-6 months later (or at least that is what happens to mine). The female will remain the same size she used to, but develop a sword and the anal fin will even resemble a gonopodium Thus they will by far be the largest ‘males’.

 

In certain species of swordtails, there is usually only one male – that is only one fish with obvious external male characteristics. The other males continue looking like small females. If/when that male dies, one of the smaller males (probably the strongest one) begins to develop male characteristics in a fairly short time and becomes the alpha male.

 

As far as Neoheterandria formosa goes, I suppose it makes sense for female N. elegans to look like males. I keep this species and the females can be really hard on each other. I try to keep so many together, that the aggressions don’t cause casualties, because there are many ‘victims’ for the aggressive female(s) to harrass.

 

My name is under my avatar.

[plesner]

I’d love to read that one too.

[plesner]

I’d love to read this one if/when it becomes available.

[plesner]

There’s a quite big chart of shrimp species and which of them will interbreed here:

 

http://www.planetinverts.com/ShrimpBreedingChart.pdf

[plesner]

My reaction can be summed up in just one word: WOW

[plesner]

Could I please get to see that one too?

[plesner]

I would love to read a copy too.

[plesner]

QUOTE (paul thompson @ Apr 24 2012, 03:12 PM) <{POST_SNAPBACK}>

Interestingly, Xiphophorus (certainly helleri) doesn’t have X Y (sex) chromasomes. The sex of swordtails is determined by autosomes. The old TFH booklet on Genetics has some fascinating info on this . . .

Can’t give you any more info as I’m working overseas and the book is at home in the UK – worth a read if you can get hold of an old copy.

Which book are you referring to? This one by any chance:

Genetics for Aquarists
Author Dr. J. Schroder
Published by TFH, 1975, 125 pages
(and I think it was possibly re-published in 1991?)

Whether this is the book you are referring to or not, I do now know that I’m missing a book in my collection. I do find stuff like that rather fascinating and would love to read it.

[plesner]

I’d say either Puntius lateristriga (spanner barb or T-barb) or Puntius kuchingensis (false spanner barb).

You can see both here:

Puntius lateristriga

and

Puntius kuchingensis

Personally I think Puntius lateristriga is the more likely of the two. It does indeed look rather old. I have never seem them with a body shape quite like that.

[Author]

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