Re: Notho egg development

["Ron @ CCK" <ronwill at starhub_net.sg>]

Hi Barry & Brian,
Thanks for the response.  I'll continue to make observations but
meanwhile, a few more questions...

> From: Barry Cooper <bjc3 at cornell_edu>
> I can't really answer your question, because I've never studied the
> viability of eyed-up eggs over time. The cause of belly sliders is still
> controversial
I was advised off-list to ensure cool hatching with high oxygen level as
prevention, and am experimenting with gentle aeration.  I'm not sure if
water parameters are at play but have a look at the following link and
see if this dummy here missed out the obvious (my mains are served by
Choa Chu Kang Waterworks); http://www.pub.gov.sg/brought_to_you.htm

> ... although I think a lot of people would agree that incubation
> for an inappropriate period of time might be one cause. That might be too
> short a period, or too long.
Most of the incubation period found online are more appropriate for
countries enjoying cooler (cold?) climates, hence I can only hazard a
guess for the timing in warmer areas and the difference can be
substantial.

Take for example, Simpsonichthys magnificus (which I'm attempting to
breed), which lists incubation at 8 Months, 5 Months and 7 WEEKS(!) at
24°C/75°F, 27°C/80°F & 30°C/86°F respectively.  A six degree difference
here hypothetically shortened the incubation by almost 6 months and
there's no mention of 32°C (wanna guess?).
(http://killifish.vrx.net/breeding/annuals/times/).

> I would suspect that in your warm situation
> prolonged incubation would result in progressive death of embryos and thus,
> failure to hatch.
So what do I use as a yardstick then? or should I just dunk the
well-developed eggs anyway and cross my fingers.

> that if I look at, or try to hatch, VERY old batches of eggs (say two
> years) from species that are normally regarded as short to medium
> incubation period, all of the eggs will have disappeared.
I tried peat incubation for GAR N'sukka & Baissa for 2mths, which yield
2 & 4 frys over a 1-week wetting period (when I collected almost 20
eggs/bag).  Not sure if I had over-incubated.

> ... There are some
> species, though, where very long incubation periods are the norm and eggs
> can survive, under the appropriate conditions, for many years.
What about those well developed, eyed-up eggs that simply refuse to
hatch?  I tried babysitting them (film canister in pocket) and adding
microworms (where the CO2 supposedly induces hatching).  Nothing works
and I see lesser viable eggs upon rewetting after a 2-wk interval.

======================================================

> From: "Brian R. Watters" <bwatters at sk_sympatico.ca>
> Once the Notho eggs reach the final stage of development and you can see
> clearly eyed embryos, they will only last another few weeks (about 4 weeks
> maximum ??) in the peat before they will die.
That's not a very wide window, is it?

> ... If your N. eggersi eggs are
> eyeing up in about 4 weeks, I would suspect that leaving them for 3 months
> will result in a very poor hatch because most of the embryos will not be
> able to survive an additional 2 months in a fully developed condition.
But I don't suppose they'll hatch in peat prior to wetting... or do they
attempt it anyway?

> belly-sliding may be due to something other than incubation/development
> time. For example, is your peat very wet ? In my experience, that can also
> result in a lot of belly-sliders (i.e. the eggs develop under conditions
> that are effectively like water incubation).
For N. eggersi (when harvest was good and eggs divided into 4 lots), I
tried both dryer 'pipe tobacco' and slightly damper peat (but doesn't
stick to hands, not dripping wet).  At 4 weeks and 6 weeks incubation,
the 6wk-lot has slightly lesser sliders.  Hatching water/conditions were
similar in the 2 trays, without aeration.  Is there such a thing as
'zero sliders', I wonder.

Thanks & regards,
Ronnie Lee
Singapore

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