Re: [Killietalk] Nothobranchius egg sizes?

["Robert Goldstein" <rgoldstein at rjgacarolina_com>]

Lee - You mean YOUNG mature fish, not immature fish (which can't lay eggs).
Egg sizes vary considerably in many species of fishes. Years ago I did a
manuscript on Atlantic & Gulf coast fishes that included considerable
biological data, and as I recall there was a great range in published egg
diameters for almost all the fishes I reviewed.  I've seen large native fish
of a single species produce larger eggs than smaller fish of the same
species. I think the ability of the mother to pack a lot of yolk into the
egg is important, and that seems to increase with size, vitellogenesis
capacity, and general health. Fish also differ in the number of eggs they
produce at one time (number of eggs that can ripen in 24 hrs and thus be
ready for laying), with larger fish producing larger spawns than younger
fish. BTW, I think Scheel also recorded a range of sizes for fish eggs. This
is not to say egg sizes are not useful. As Brian pointed out, Aphyobranchius
janjapi eggs are pretty tiny compared with, say, N. rachovii, but even when
ranges overlap, one can often see a difference in the average size of the
egg of different species. It's just not easy to quantify simply because of
the ranges encountered. - Bob G.


----- Original Message ----- 
From: <LeeH920226 at aol_com>
To: <killietalk at aka_org>
Sent: Friday, July 09, 2004 10:40 AM
Subject: Re: [Killietalk] Nothobranchius egg sizes?


>
> In a message dated 7/9/04 10:18:41 AM, bwatters at sasktel_net writes:
>
> << And, no, I do NOT regard "thierryi" as belonging to the genus
> Nothobranchius - there are many good reasons to place it in a different
genus. >>
>
> I knew that, but I believe the question was about Nothobranchius per se.
So
> perhaps Aphyobranchius also does not fit the category. So the question is
what
> is the best measurement available for N. janpapi? If someone can send me
an
> egg or two, I will measure it using the microscope. I do not discount the
> estimate made, just that I want to have the data on the same basis. My
main reason
> for continuing to do this is that I still consider the egg diameter to be
a
> fundamental characteristic of a species that is often neglected by species
> describers, mainly because they never see an egg. The caveat about egg
diameters is
> that they are sometimes smaller from immature fish but stabilize at a
narrow
> range for mature fish. Different collection sites for supposedly the same
> species have also shown differences that I worry about -- not enough to
lose sleep
> over. For a table of egg sizes see my article in JAKA Jan/Feb 2000 Volume
33,
> No. 1
>
> Lee Harper
> Media, PA
>
> To join the AKA see http://www.aka.org/pages/join.html
> Archives are at http://fins.actwin.com/killietalk/
>
>



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