controlling the sex of fry???

[Magnum Man]

so, I have a population of wild type sword tails, one of my 1st attempts at breeding with the purpose of reselling… breeding has been regular in my group, but at least to start with, females greatly outnumber males… with ornamental fish, often the male, is the prettier fish, so any hope of resale requires them, and one would think a 50-50 mix would be nice, however it may not be natural, as one male can service several females…

I started reading up on controlling the sex of the fry, and it seems most. practical with egg layers, than with live bearers… I’ve not manipulated any of the environmental conditions yet, but reading AI, hasn’t been much help, curious if the live bearer keepers have any suggestions???

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my other thread on my swords here…

dark ages weaponry… ( the swords )

a while back, I got a small group of wild type swords ( Rio Atoyac )… I instantly fell in love… and my original group of 3 grows to 8 today… also arriving today is another group of 5 wild type from another region, that are claimed to grow to 6 inches long, that will be going into a different...

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[GaryE]

Welcome to swordtails. I think we discussed this here before, but swordtails have an early wave that sexes out at a few months and dies young, and a second wave that sexes out between 6 months and a year of age and lives longer. There seems no way to rush it, and when I sold swords, I warned buyers about that. They call for patience above all else. Many of what I thought at 6 months to be 100% female groups ended up being more or less even...

It can drive you nuts.

 

[Innesfan]

More vexing is when the gender ratio is skewed toward males, which is common in some wild swordtail populations. As @GaryE mentioned, we've disccussed this before and this is what I wrote then about a wild Belize population of swordtails. I should note that though I've always had success with the 2-in-a-bowl method--as have many hobbyists over the years--others report little success with it:

<<
The 2-in-a-bowl method worked for me with the Rivulus, Fundulopanchax and Aphyosemion species that were throwing skewed ratios, and one population of exceptionally gorgeous wild Belize swordtails that I got from the late great Joanne Norton, who warned me she was getting skewed sex ratios. She sent me 24 juves that wound up 23-1 male. I bred the one pair and raised some 3-to-a-bowl and got 60-40 males, a decided improvement. So if Dr. Joanne Norton--who cracked the angelfish genetic code and did such extraordinary work with livebearers--couldn't crack the sex ratio problem, well, we're in good company.>>

 

[GaryE]

I think the sex ratio problem has ended my keeping of more species than any disease, any cycling problems or any parasites combined. I've hit the dead end of breeding a species because I liked keeping it and getting all male or all female broods so many times, even in species that had given me even ratios before. That's helped by my being a hobbyist with limited resources. I have space to raise maybe 20 young, but not 200.

I think I've done enough 'work' over 34 years with Aphyosemion zygaima to be able to say water hardness plays a possibly crucial role in sex ratios. But doing the things that worked time and time again with zygaima with their close relatives A. ogoense and A. loussense didn't work at all. So species by species, and a need for enough magic bullets to keep an army happy.

I have read confident statements that it's temperature, hardness, pH, diet, and water depth. Could be, for the species the people reporting worked with - or a combination of all of the above, some of the above...

What controls sex ratios isn't mystery at all. It's many mysteries.

 

[Magnum Man]

I’m not even sure I have a problem yet, just trying to get perspective…

the bulk of my tanks are on RO water, but my live bearers are on straight rock hard well water with normal for my area, potential agricultural pollutants… I’ve heard about male and female hormones being present in many areas drinking water systems… ( that is likely not a problem in my area )

and one would think fish that pair up, would naturally produce 50 / 50, male - female, but fish that a prominent male reproduces with several females, that nature would provide a higher number of females… these are thoughts in “pure form” however different climatic conditions could skew the results, as what the natural ( outside our aquariums ) results from these changes ie. rainy seasons, droughts, etc., actually do to the fish…

I don’t really understand the 2 and a bowl idea… would it really matter if there are one daddy, or 3???

 

[TwoTankAmin]

One reason I have had some success breeding the B&W Hypancistrus is due to the fact that it takes a females about two weeks after their last spawn to have eggs ready for the next spawn. However, the males who tend the eggs/wigglers and fry with some level of yolk sack still present need about a month before he kiccks free swimming fry out of the cave.

The result is that a good ratio is 2 males/1 female. However, there are three potential strategies one can use when spawning these fish. The most basic is to have 1 male and 21 female. But this requires that one decide which male and which female if one selects from a group of both sexes. More ideal is a 2 male/1 female ratio, But this also means that one must choose the three fish from a group. The next option is to have a group with multiples of both sexes.

With a group nature has made things such that the best/strongest males and females will select each other and the result should produce the best quality and healthiest offspring.

One advantage to working with these plecos is that they do all of the work. I have always preferred to work with groups. This mean my part was not do do things which might discourage or prevent them from spawning. While this did produce a fair number of fry, it most certainly did not look to produce the maximum numbers. There were two methods for doing that. The first was to work with pairs or reverse trios. But that might mean moving the fish around so there was always one female ready to drop eggs and one male not tending offspring.

However, there is ine more trick one can use to maximize the numbers of offspring. When dad is tending eggs, he will not spawn again until the fry are gone. So, if when one sees a dad one eggs, but removing the eggs or even wigglers fro m his care, he would be ready to spawn again. So instead of having to wait a month between a male's spawning. One can pull the eggs early making him willing to spawn again. By having a 50/50 mix of the seces t=one can maximize output.

This was something I never even thought of doing as I choose to work with gorps because they are much more capable of deciding which who should be spawning with whom. I preferred to let nature make the selection as it will produce better quality offspring than I might get if I chose instead.

I am a big believe in nature working out the best way for any species to produce the strongest offspring. That is why some fish pair, some fish scatter eggs, some fish mouth brood etc. How any species has the potential to keep the species going and insuring the offspring will almost always be the best quality is the result of a lot of time for the specific method to come into being.

I really liked the fact that my plecos pretty much did all the work in terms of reproduction. I never had issues with a misbalanced number of sexes.

 

[Innesfan]

I don’t really understand the 2 and a bowl idea… would it really matter if there are one daddy, or 3???

The strategy doesn't involve the parents. It's for raising fry: two or three fry to a vessel for the formative early weeks when gender is purportedly being set.

 

[TwoTankAmin]

correct me if I am wrong here. But my understanding is if a group of swords is all female, one or more can chnage their sex? This may only be true for some sword species?

 

[GaryE]

Sex change in swords certainly happens, but what happens more is late blooming males people thought were female. When it took 13 months for Xiphophorus maeyi males to appear in the group I bred, that kind of thing'll start rumours.

 

[fishorama]

Not that I have much experience breeding livebearers, but with some cichlids there seemed to be a temp or hardness factor to gender ratios. We had fry batches that were almost entirely male or female. We were never good at checking which parameter influenced the outcome, seasonal differences? We often had fry grow older than we would have liked & could often tell.

 

[GaryE]

You could do like the fishfarms sometimes do and wallop the water with hormones....

I knew a breeder who had worked in the technicolour Discus business who was constantly getting mad and calling me a purist because I refused to use hormones in my tanks. He seemed able to make his fish male, but had no recipe for females. He was trying to get a home business going after he'd moved here, selling pigeon blood and other colour monstrosity Discus. He sure knew how to make them colour up before sales, but then they'd mysteriously fade. He blamed a lack of water testing!

I probably should have kept logbooks and notes on my fishbreeding. I'm not a list maker, but the data might have been useful. I flipped through the indexes of the Baensch Atlases a while ago, and I've bred well over 200 species. I'd breed them, raise young to a saleable size and take them to the club auctions. So I got to see the sex ratio puzzle a few times. I have had about 40 species that I settled in with and bred for at least 3 generations. That's a process that becomes possible when you've kept fish for 59 years.

Research by serious hobbyists suggests my beloved Western African Pelvicachromis (krib group) are temperature influenced, with 26 ideal for even ratios. But I have had occasional good ratios at 22 with some of them. Sometimes. The same rule has worked with Apistogramma. But beyond that, the world of Cichlids has been gambling on ratios. My downtown Montreal water was pH 7.4, well buffered and 140ppm. Western Montreal was pH 6.8, 80 to 100 ppm. Here, it's pH 6.8, 65 to 80ppm. In each house, I've had difficulties with different species, even getting some to breed let alone getting even ratios afterwards.

We'd like to say it's water OR pH, OR temperature, but what if it's a subtle blending of all of the above?

 

[Magnum Man]

wouldn’t a close inspection of the male organ area be a clue, even if the fish looks to be female, or does that actually develope later as well???

 

[GaryE]

It develops later. You sometimes see a spot of pigment develop in the anal fin area, and then spread as the gonopodium begins to form. They often have pigment in them. You also get a thickening of the rays in the fins before the organ forms, but not always and not in every species. You get the same pigment line forming where the sword will develop later, as swordtails usually have a dark edge on the extension. But I never found it helped much because when the genetic triggers went off, the process was fast anyway. You get like a week's warning, and by then, the fish is adult sized.

By the time you decide that yes, that's what you're seeing, the gonopdium is starting, and the sword too.

My X. maeyi were huge swordtails, the biggest I ever kept. I had them in an eye level 75 and had over a year to look at them in hopes of having males. People wanted pairs and they were using up tank space. I was motivated. I could identify no warning signs until boom, in a week, I had my males develop.

I raised aquarium trade hybrid swords, X helleri, X montezumae, nezahualcoyotl, xiphidium, alvarezi, and clemenciae from the swordtail group, and saw the same things.

 

[Magnum Man]

I see a new batch of babies in the sword tank ( this makes 6 or 7 batches ) still no lil sword tails showing, on any of the older ones… an interesting feature of this type, is they have white lips, which is still there, but fades as adults, but juvinals all have bright white lips…

 

[Back in the fold]

Makes you wonder how they’ve even been kept going in the hobby . Fortunately a few guys know what’s what and have seen to it .