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fathead minnow gender / sex ?


10 replies to this topic

#1 JackieFisher

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Posted 16 March 2019 - 12:28 PM

I have a video of 2-3 inch fatheads swimming around and these have never been reproducing for months (winter-spring, room temp). They look kinda  ambiguous.

I think some are male-ish by the more blunt head and dorsal fin, and some lack these features. 

Reproductive tube-wise they all have a tiny bit of protrusion down there. It is possible they are suffering from agricultural pollusion which contains sex hormones.

Any suggestion would be appreciated!



#2 Matt DeLaVega

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  • Ohio

Posted 16 March 2019 - 02:57 PM

Try feeding them heavily on live foods or frozen foods for a couple of weeks and then do a large water change and increase day length. Sticklebacks are bullies. Maybe they are causing stress. Are there cavities for them to spawn in? Stacked tile, pvc pipe, clay pots? I see a bit of stacked shells, but I would add a good bit more. If you are primarily feeding flake food they may not be getting the nutrition they need to come into spawning condition. If you go into detail about your setup and husbandry practices, I bet someone around here could give you some pointers.


The member formerly known as Skipjack


#3 JackieFisher

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Posted 16 March 2019 - 11:39 PM

Try feeding them heavily on live foods or frozen foods for a couple of weeks and then do a large water change and increase day length. Sticklebacks are bullies. Maybe they are causing stress. Are there cavities for them to spawn in? Stacked tile, pvc pipe, clay pots? I see a bit of stacked shells, but I would add a good bit more. If you are primarily feeding flake food they may not be getting the nutrition they need to come into spawning condition. If you go into detail about your setup and husbandry practices, I bet someone around here could give you some pointers.

 

Thank you very much for the very helpful tips.

Daylight length is 15 hours here, but I do not have consistent room lighting; they are in the living room with large windows but facing north. I feed only flake food, not a whole lot, as they are always super eager for food. There are two of the large white oyster shells as you saw in the video.

Could you see despite the blurry image that both sexes are present?



#4 JackieFisher

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Posted 16 March 2019 - 11:43 PM

https://www.fondries...xic_fishfem.jpg

 

 

I see that the 'males' look like the one (B) in this picture that is feminized by pollusion.

The water these guys are from is close to farms.

I hope were there any effect it is not permanent



#5 Matt DeLaVega

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  • Ohio

Posted 17 March 2019 - 01:15 AM

I don't know enough to go into the sex hormone thing. I doubt it, but that means very little. Unless the males are triggered to believe it is breeding season, they aren't going to look like breeding males in photographs. The look of a breeding male has to do with much more than age. Environmental conditions must be right for them to change. They typically change yearly during breeding season and revert when not breeding. Unless you are making changes to stimulate them, I wouldn't jump to the conclusion that they are feminized from agricultural hormones. Fathead minnows are very often close to farms. They are probably the most stocked fish in the country, and are primarily stocked in farm ponds as forage fish. The use of hormones in agriculture is not as widespread as people like to think. More common in huge feedlots and huge dairy, uncommon in average size family farms. You know which is in your neighborhood, but unless they are large factory type entities I wouldn't at all suspect agriculture as the culprit.


The member formerly known as Skipjack


#6 JackieFisher

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Posted 17 March 2019 - 06:09 PM

I don't know enough to go into the sex hormone thing. I doubt it, but that means very little. Unless the males are triggered to believe it is breeding season, they aren't going to look like breeding males in photographs. The look of a breeding male has to do with much more than age. Environmental conditions must be right for them to change. They typically change yearly during breeding season and revert when not breeding. Unless you are making changes to stimulate them, I wouldn't jump to the conclusion that they are feminized from agricultural hormones. Fathead minnows are very often close to farms. They are probably the most stocked fish in the country, and are primarily stocked in farm ponds as forage fish. The use of hormones in agriculture is not as widespread as people like to think. More common in huge feedlots and huge dairy, uncommon in average size family farms. You know which is in your neighborhood, but unless they are large factory type entities I wouldn't at all suspect agriculture as the culprit.

I agree. That is very informative and helpful. Time to buy new foods!



#7 JackieFisher

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Posted 05 April 2019 - 04:20 PM

I improved water, lightning, cover and rations and after 3 weeks there's still no breeding



#8 JackieFisher

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Posted 14 May 2019 - 06:25 PM

I now suspect perhaps they are all males:(



#9 JackieFisher

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Posted 20 May 2019 - 05:19 PM

Try feeding them heavily on live foods or frozen foods for a couple of weeks and then do a large water change and increase day length. Sticklebacks are bullies. Maybe they are causing stress. Are there cavities for them to spawn in? Stacked tile, pvc pipe, clay pots? I see a bit of stacked shells, but I would add a good bit more. If you are primarily feeding flake food they may not be getting the nutrition they need to come into spawning condition. If you go into detail about your setup and husbandry practices, I bet someone around here could give you some pointers.

Thanks for your tips. I 'll provide more detail and hopefully some will spot the problem:

 

- day length is 15 hours

- temperature 68-79 (room)

-water change: 10% every 4 days, 80% every 12 days. filtration: pump+carbon filter; airstone

-food: pellet and flake 3 times a day

-stickleback is removed; there was a veil-tail goldfish in the same tank

-cover for spawning: lots; fish are fighting for these sites

-15 gal, 5 fatheads

-sex: 3 larger ones (3 inches) look male-ish;  2 smaller (2-2.5 inches) I am unsure, they are more slender and lighter in color

thanks



#10 JackieFisher

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Posted 09 June 2019 - 03:10 PM

Please help

#11 JackieFisher

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Posted 09 June 2019 - 03:10 PM

#7
Right now at least one male has developed breeding tubercles and dark pattern, but it is unstable and goes away occasionally.
I am not sure those females are actually males instead.
They are kind also territorial . One female would fight for caves.
every fish including obvious males have a little ovipositor like protrusion don under.
Not sure if i should persist. There are tons



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