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
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