XY (Male) x XX (female) chromosomes = 50% F 50% M

[Adrienne Kang]

As stated in the subject

XY (Male) x XX (female) chromosomes = 50% F 50% M

but why there are less than 50% males in most spawns?

does pH level affect their sex determination as other fishes do?

I read that low pH is suitable to produce more males.

Any explanation to the % of M vs F in spawns?

[Myron Tay]

The jury is out on this one, although I think there is concensus that it is more of a environmental issue rather than a genetic one.

[Adrienne Kang]

Anyway I would like to find out how many chromosomes do Betta have?

[Dr Hsu]

I don't think fish are XX and XY...something like WW andWV or some other and I think the female is the one with the short chromosome. Could be wrong as I didn't pay very close attention to fish genetics in class

As for ratios....well they're theoretical so you can get anything from 0 to 100% in any one spawn. As for the pH theory...I have had 100% females at low pH, down to 3.5 - so that kind of turns the pH theory upside down!

[Adrienne Kang]

"There are no unequal chromosomes in bettas that might be sex chromosomes. However bettas seem to follow the XX, XY model since they normally produce 50% of each sex. Bettas can produce surprises. Id young males are bred with old females, the resulting offspring are mostly males. If the fry are held at abnormal conditions during the first 6 weeksm an overwhelming % of males is again produced. And of females are partially ovariectomized (most of their ovaries cut away), they transform into fully functional males"

(Lucas 1983)

It was a rather interesting read [ag]

[howechiat]

Normally which week will a fry exhibit its gender? The idea that it's determined by the environment goes against intuition...

[Sebas]

i strictly believe that the gender of bettas is not 100% dependent on chromosome only.
Environmental factors and like what Dr Hsu has mentioned previously, hormones may also play a part. Unless someone finds an attractive reason for completely understanding the betta genome, research on bettas will mostly be based on interest and curiousity.

[Myron Tay]

Not a question of genetics, but one of environment. See thread on this here:

http://www.bettaclub.org.sg/forum/topic.asp?TOPIC_ID=211