Sex Change?

[Bilbo]

Has anyone witnessed a genuine sex change in Agassizi?

2 years ago I got 6 young Agassizi and as they grew they all seemed to be female, I acquired 2 males at one stage but they both have long since died and lasted only about a month.
All of them have been definite female size, colouration and fin shape but a few weeks ago one of them started to change and has grown bigger than the others and is taking on male colours including a 'tefe' or wild blue tail.

If he was a sleeper male why did he wait so long to change? It has been a female only tank for close to a year.

 

[tjudy]

I have not heard of this with Apistogramma species, but there have been documented cases of east African cichlid females becoming phenotypic males at an old age. I think that is has something to do with the hormones controlling female secondary sex characteristics no longer besing produced in enough quantity, and the hormonal balance shifting to male secondary sex characteristics. The fish, however, were not reporductive males.

 

[Sharpfish]

Is it possible that while your males were still alive they spawned unbeknowst to you? This could be an offspring that is just coming of age. Does the coloration match up with the deceased males?

 

[Mike Wise]

There are several confirmed reports of apiso species producing viable eggs and later in life changing to males and producing viable sperm. It probably happens more than we realize. To be a confirmed sex change, there has to be no possibility that other factors have come into play. The original female has to be the only female in the aquarium and produce viable fry. When it changes sex, it has to be mated to a proven female - one that has produce viable fry in the past with a different male. It has to produce viable fry with the proven female.

More common is delayed masculine secondary characteristics (sneeker male) caused by more dominant males in the aquarium. In these the fish is a male and can fertilize eggs, but retain juvenile/female features to avoid aggression from other, more dominant males.

As mentioned before, older females can develop masculine secodary sexual characteristics, but still have feminine primary sexual characteristics (ovaries, etc.) and thus cannot fertilize eggs.

Cichlids are interesting fish. For example, if I remember correctly, there is a report of an Accaronia nassa specimen that successfully layed viable eggs, then successfully fertilized HER OWN eggs (only fish in the tank!), before becoming a fertile male.