male / female ratio very important?

[duendecillo]

before I started fish keeping, I read a lot on this forum, and some people mentioned you should have more females than males, so that the females don't get bothered too much...
but the problem is: I keep getting about 90% male fry
I find it a bit useless to go buy female guppies...

so questions: how come I get 90% males?
can I help this some way?
is it such a bad thing to have more males than females (there's not much chasing going on in the tank)

 

[Tempestuousfury]

Nope. Probability, I am afraid.

Are you keeping those fry as adults?

Since they are guppies, they make for a good show tank. However, you can't hope ot breed them with 10 females to 90 males (exaggerated tank stock), because the females would die from stress.

If you have enough room and hiding places 1:1 is ok, though...

 

[paulthegreat]

I do not know but since I watch a lot of Discovery, the thought of Crocs comes to mind. Their babies are sexed by temp. Maybe it could have something how warm the tank is??? With a different temp. you may get a different ratio.

 

[yhbae]

I am curious, what is the pH in your tank that produces 90% male?

In any case, usually if there's enough fish in the tank, aggressions are distributed throughout regardless of their ratio. If your tank is setup as a breeder setup, I would add more plants (such as java moss) and add more of the same species, as long as you are not overstocking the tank.

 

[lady_tanksalot]

i agree with paul

the first thing that came to mind was temerature, not sure if it does apply to fish but it definatly does to some other species

 

[duendecillo]

thanx for the replies
temp is 25°C (I think that's 77°F?)
and PH is 7.8 - 8 (have there ever been real studies about this)
the tank is a 235l tank with guppies, platies, cories and some zebra danios
it's not intended for breeding, but occasionaly I put fry that I find in the filter, in a breeding net, and sometimes I let a fish give birth in a separate tank.
I do this because I like to see fish from different age in the tank, and to keep a certain continuity... but they are developing from 3/1 female/male ratio, to 1/2.
Luckily the males are more popular, so I can give these away, so now it is about 1/1.
I will try to only keep the fry with a gravid spot showing, although I don't like culling at all...

just another question then: if you see a gravid spot on a fry, is it certain to be a female, or is it possible that it changes into a male on a later stage?

 

[newfishies]

i thought that some of my guppy fry were female and the "gravid spot" turned out to be a dark marking on the surface of the body!!

 

[JoKeR]

I think PH

IIn the betta world PH is what matters to get the ratio.

 

[paulthegreat]

I think I read somewhere that with Swordtails they are all born female and then some of them change to male at a later stage. Maybe this is also true with other species. This would not explain a 90% though unless there is some other factor causing it.

 

[duendecillo]

I don't wanna mess with the ph, so I guess I'll leave it this way...
I guess a lot of breeders would like to have the ratio I have

 

[yhbae]

I'd say it is the pH that is causing your ratio as well. My pH is 7.2 and I get far more females than males... (Platies, not guppies)

 

[English Lion]

At the moment I'm getting 100% males from my female swordtail (well they all end up as males). My tank's a nice constant pH7.0 and 0ppm NO2, NO3 & NH3. I don't know what causes it but I've currently got 1 female to 4 males. She doesn't seem to mind too much as the ales spend a lot of time chasing each other away!

 

[duendecillo]

oh, okay, so I'm not the only one with this 'problem'
in fact, I haven't had one female platy fry too, so they are even worse as my guppies...
maybe if the fry see how beautiful males get, they all want to change into males...