Re:

[Mike & Diane Wise <apistowise@bewellnet.com>]

Jonathan,

If you really push your fry, sexual differences can be seen within 3 months - at
least some of the males will start to show their secondary sexual
characteristics. At this age they should have visible testes or ovaries.

Römer & Beisenherz have shown that temperature AFTER spawning is the primary sex
determinant in most apistos, including A. borellii. (See my post to this list on
11/29 that cites reference).

Mike Wise

jonathan wrote:

> I just thought that I would keep you all updated. I'm involved in the
> largest non-commercial Apistogramma borellii breeding project I've ever
> seen. I've got five 25 gallons of these cranking out clutches of eggs at a
> rate of almost one a day. I've got eight 20 gallon rearing tanks set up
> with a clutch in each. This shall be fun. I have to get them to grow as
> fast as possible, water changes daily with three feedings per day. If you
> wonder why a hobbyist would dedicate so much time to this (almost a full
> time job), it's my honours BSc thesis. Anyone have any thoughts on how
> long it will take for these fish to reach a size that will show sexaul
> dimorphism? Any biologists out there have any idea whether sex can be
> determined upon dissection if they are not sexually mature? I am
> investigating environmental sex determination by pH and temperature, (and
> reproductive behaviour in the P generation).
>
> Kind regards,
> Jonathan
>
> -------------------------------------------
> Jonathan Fung... Reef Geek
> Dalhousie University Honours Marine Biology
> Aqua Creations Inc. Assistant Manager
> writer for Marine Fish Monthly
> -------------------------------------------
> email: fung@is2.dal.ca
>
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