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Re: [Killietalk] Inspecting killifish eggs in peat
This is why I have found ring-light fluorescents around magnifiers
relatively useless. I always used them in my business (so they were
right there and available), but found they don't work as well on the
harder-to-find kinds of eggs. Many SA annuals and some savanna African
semi-annuals have eggs that cling to the peat and are really hard to
find. They build their own camouflage coating of peat. A point-source
light, like a 50W or 100W halogen reading lamp (20W may be too weak) or
the sun, and a lighted background (the white bowl) can make the
peat-covered eggs show up when the light passes through them in a very
thin layer. Wetting and viewing in a shallow Petri dish, as Lee does,
can help get the eggs loose from the peat, too. I have resisted doing
that, because I can always find them dry with the right lamp, and I fear
wetting messes with the normal diapause sequence. The bright light
probably isn't good for mature eggs with eyes, either, so I tend to bury
them back in peat as soon as counted.
A pellet's worth of peat, pushed to the far side of the bowl, and
dragged a bit at a time across the lighted center of the bowl takes
about 10 minutes, typically, and I will usually find the approximate
number of eggs in the process. I use blunt tweezers to do the dragging,
but a toothpick or blunt butter knife would work as well. The trick is
to drag a thin layer at a time, so the light shining through lets you
catch the amber glint and shape of the round egg, even if quite a lot of
peat is clinging to it.As the embryo develops and darkens the egg, they
may get even more difficult to spot. That is why I think a 50W halogen
is the minimum size for finding all eggs. YMMV (particularly if you have
younger eyes and a trained brain that spots shapes easily).
KeeHoe Leong wrote:
> I agree. Even the Notho.Janpapi is easier to find despite its size.
> (About the same size as those of clown killi.). I remember someone
> mention before that SAA's has fine spike on the surface and peat will
> get stick on to it easily.
> On Thu, Feb 14, 2008 at 2:03 PM, Joseph S. <nonamethefish at gmail_com> wrote:
>> I found Notho eggs very easy to find, but I recall a bag of
>> nigripinnis which I sifted thoroughly and could not find anything that
>> looked like an egg...except maybe one thing that could have been a
>> peat covered egg. Anyway, put them in the water, and out pop 40+ fry
>> and it produced almost as many on the rewets.
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