Re: [Killietalk] Eggs on Peat

[Wright Huntley <whuntley at verizon_net>]

George & Melanie <caraway at erienet_net> wrote

> I have been trying to store eggs on damp peat for the last couple of
> weeks instead of my usual water incubation method just to compare the
> two methods. I have some gardneri eggs (Basua & Misaje) that I have
> had on the damp peat for about 15 days now and they appear to still
> be mostly in a clear state. I realize they may incubate a little
> longer on the peat, but I thought they should show some development
> by now. Does anyone out there have any suggestions why the eggs have
> not shown any development yet?? Or is this nnormal?? Thanks, George

Hi George,

Annuals, like *Nothobranchius*, *Simpsonichthys*, etc. have developed 
the ability for the eggs to go into a sort of suspended animation, only 
to resume development after the dry season is over. The various stages 
of this are called by the name "diapause." Literally, it means "a period 
of physiologically enforced dormancy between periods of activity" but 
each development stage tends to be given a diapause stage number, even 
if some are pretty active.

Semi-annuals, like most of the *Fundulopanchax* can also go through a 
somewhat dormant stage when stored in good contact with air. This period 
of inactivity tends to be less firm than among the true annuals, which 
is why they are called semi-annuals by some authors. As natives of the 
sometimes dry savannah (a tropical or subtropical grassland containing 
scattered trees and drought-resistant undergrowth), they have partially 
adapted to the drought conditions so some eggs survive in unusualy dry 
years.

True annuals need a significant reduction in access to oxygen (or 
increased CO2, proportionally) to cease dormancy and hatch. The eggs may 
last for many months with no further change (after they are fully "eyed 
up") until they are dunked. In many cases. enough activity goes on for 
them to deplete their yolk energy and hatch as belly sliders or with 
deformed spines when kept beyond the proper hatch time (based on 
moistness and temperature, for most species).

I have never (knowingly) experienced true annuals "hatching in the peat" 
but that has happened to *Paludopanchax* and other *Fp.* for me. I may 
tend to keep them a bit too moist, but they are intolerant of extending 
their hatch date too far, and I can find (with great difficulty) 
carcasses of tiny hatchlings when I examine too-long-stored peat.

Development on damp peat seems to not be a good idea for 
*Chromaphyosemions*, Lamp-Eyes, Pupfish and many other non-annual 
killifishes that originate in more permanent waters. Incubation in water 
has always worked best for me.

Wright

--
Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net
                      760 872-3995

"If you ask me, I know of only one class of workers who are overpaid and
underworked -- college professors."
                   ---  Walter Williams

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