RE: Notho egg development

["Brian R. Watters" <bwatters at sk_sympatico.ca>]

Ronnie Lee wrote:

>
> I was advised off-list to ensure cool hatching with high oxygen level as
> prevention, and am experimenting with gentle aeration....
>

Use shallow trays for hatching the eggs (about 2 inches water depth) and the
relatively large surface area should provide adequate oxygen content. I
would not use aeration at all.

>
> 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?).
>

Development times of Notho eggs depends on so many variables (most of which
we still don't understand) that the so-called "incubation charts" can only
be used as very rough guidelines. Keep working with a species, check the
eggs regularly for signs of development and develop a knowledge base for the
conditions that prevail in your fish-room. There is no substitute for
experience.

I have raised very large numbers of Simpsonichthys magnificus and I only
ever had 3 fry hatch at 6 months incubation. Most hatched after 9-12 months
incubation.

>
> > 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?
>

No, it is not a very wide window and that is why checking the eggs from time
to time is a good idea - at least until you develop the knowledge base
mentioned above.

>
> > ... 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?
>

They won't hatch in the peat, the embryos simply die.

>
> > 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.
>

Yes, there certainly is such a thing a 'zero sliders'. It seems that
moisture content of your peat was not a problem. You may be trying to hatch
them too early. Also, how much peat did you have in the hatching container ?
I always ensure that I have a layer of peat on the bottom of the hatching
container, a good half inch or more, and if there is insufficient from the
peat containing the eggs then I add a bit more. I have found that attempting
to hatch Notho eggs with little or no peat in the hatching container results
in either a whole lot of belly-sliders or the eggs are reluctant to hatch at
all. And, no, I don't know the reason for this, although it has been debated
on this list before.
___________________________________________
Brian R. Watters
University of Regina
Regina, Sask. S4S 0A2, Canada
Ph: (306) 584-9161 (home); (306) 585-4663 (work)
Fax: (306) 585-5433
E-mail: bwatters at sk_sympatico.ca


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