Female ID

[Poe]

Following the advice of Neil identifying pandurinis females I had a look at the rest of my females.
I found that all of them, cacatuoides, agassizii and borelli opal had a black margin in the ventral fin. It´s great to ID the sex so simple. Is it always so? Is every apisto with this black margin a female?

Regards

 

[Neil]

Ahh! If life were only that easy. The black edging on the front of the ventral fin is a very good diagnostic tool to differentiate gender, but should not be the only characteristic that you use. Numerous species of Apistogramma and other Dwarf have this marking in both sexes through their life or in young specimens. Additionally, the markings that an apisto displays are related to mood as well as a stable morphological identifying mark. For example, if several males are in a tank together, one will usually become dominant and terrorize the other males :evil:. For their own defense, sub-ordinate males will sometimes take on the characteristics of a female. These "sneaker" males can then escape injury or death in a closed system by making the dominant male less concerned with their presence in his territory. Once the dominant male dies or is removed, one of the sneakers will develop his full male characteristics.
So, although it is a good description characteristic, it should be viewed in combination with other factors to make a solid guess of the fishes gender. Identifying the form or species is similar in that there are so many closely related species it requires several elements to ID them properly.
Neil