Male to female ratios in nature....


Mmathis

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Maybe some of you who breed koi or goldfish can chime in, but I was wondering what kind of gender ratio you would normally find in nature -- that is, if we weren't culling and/or selecting for gender.

I look at my goldfish.....30+ fish. I have no idea whether I have males or females, and I've never witnessed a spawning, but I still get baby fish. Well, to say I don't know what they are isn't exactly true as I'm pretty sure I have one Ryunkin-type that is a female, but other than that, they're just all FISH in the pond. I can't tell anything from their shapes, either, as they all look the same [except this one Ryunkin]. But surely, out of 30+ fish, she isn't the only female.

So, I was just curious.....
 
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Mmathis

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Thanks, @bettasngoldfish, but what I was more curious about was the natural ratio of males to females. But next time I suspect spawning, I will look for breeding stars (hope they're not too hard to see on a goldie....koi are probably more obvious).
 

addy1

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I watch them chase all the time, a few times caught the spawning frenzy. I have see the bumps on the fish off and on, which is males, but only on the bigger fish. The small ones it is hard to see.
 
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Thanks, @bettasngoldfish, but what I was more curious about was the natural ratio of males to females. But next time I suspect spawning, I will look for breeding stars (hope they're not too hard to see on a goldie....koi are probably more obvious).

Yea sorry Maggie, I don't know the answer to your question :oops: I just thought the info might help you figure out what you have in your own pond ;)

I have seen breeding stars on my mature males, never on the younger/smaller ones. If you check the link I provided you can see a couple photos of them on a shubunkin. They also talk about other ways to determine what sex your goldfish is but I think the breeding stars are the easiest way.
 

Meyer Jordan

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Thanks, @bettasngoldfish, but what I was more curious about was the natural ratio of males to females. But next time I suspect spawning, I will look for breeding stars (hope they're not too hard to see on a goldie....koi are probably more obvious).

This is another one of those 'It Depends' questions. Different fish specie have different ratios. In some species all of the fry are born either male or female, with certain individual fish changing sex as they mature. Another factor is the age of the fish. Female fish live considerable longer than male fish. The mortality rate for males due to age is quite high in some species. And finally, there is some who suspect that environment may play a big part in the sex ratio in a particular body of water.
 
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Meyer Jordan

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Interesting info Meyer :bookworm:

I have no idea on any of that but if I were to guess male over female living longer I would guess the males would live longer. I really don't have a clue why I think that I just do :LOL:

In captivity they likely do, but in the wild, female longevity has been proven. In one specie of Flounder, at age 1 year males comprise slightly over 50% of the population, by year 6 this has been reduced to less than 10% of all 6 year old flounder.
 
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In captivity they likely do, but in the wild, female longevity has been proven. In one specie of Flounder, at age 1 year males comprise slightly over 50% of the population, by year 6 this has been reduced to less than 10% of all 6 year old flounder.

Wow, That's a big difference in numbers. Any idea what is happening to the male population?
 
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Meyer Jordan

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There's also the issue of pollutants in our waterways that are causing an imbalance of more females over males...
Here's one article I found after a quick search.

http://ec.europa.eu/environment/integration/research/newsalert/pdf/144na2_en.pdf


.

Although the article concerns UK waterways, this is also a major problem in the U.S.. It not only affects fish but also amphibians to a greater extent. This same type of pollution is also, at least, partially responsible for the pollution of the majority of wells in the U.S.
 

Mmathis

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One thing I've read is that the gender of fish is determined at a certain and very specific point in their development. It has to do with water temperature. I don't recall if that was for ALL fish, but it was for goldfish.

That's how turtle gender is determined. This is how I can remember it: HOT chicks [females], COOL dudes [males].

Not to compare humans with fish, but as a population, there are more male children born than females. But male babies also are more prone to death, and/or complications, and aren't as strong or as able to survive as are girl babies under a similar set of adverse circumstances. As a retired OB nurse, I remember that when we'd get a mom with a high risk pregnancy, we'd breathe a sigh of relief if she was carrying a girl baby, knowing that a girl was more likely to "make it."

So, apparently all GF eggs start out neither male or female, but the environmental factors at play while they are developing will determine their gender. But if you look at it that way, out of any given batch of eggs, you'd get almost all males or almost all females. Still not answering my search for the truth, though......

So with fish is one gender, maybe weaker or more prone to death, complications, etc.?

IOW, if you took every fish in that "feeder tank" at the pet store and ran DNA testing to determine gender, what kind of ratio would you get? Surely all those fish would come from different sources which would increase the chances of having sexual diversity within that group.

@fishin4cars Do you have anything to add?
 
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fishin4cars

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Temperature relation to development is very well known in many species of fish and reptiles. In nature this helps assure the population of gender and sibling crossing is naturally balanced to some extent. In most research you will find that eggs/fry that develop in cooler waters will produce more males, In warmer water more females. In some limited species the gender development can be as much as 100% produced can be a single gender. Now how does this relate to goldfish. I don't have a clue. In my own personal ponds I usually find that naturally I end up with about 1/3 females and 2/3rd males in both goldfish and Koi. On a side note breeding season is here for us this far south. I have noticed both Koi and goldfish spawning already in almost all the ponds. Best time to observe spawning is right at dusk until shortly after sunrise. This is when the activity will be at its peak and when it's easiest to pick out who is who in the breeding group. Also it's the best time to collect the eggs.
 
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