Egg size increase with female's maturity?

kkorotev · Post by **kkorotev** » 21 Aug 2004, 00:35

Will the size of the Scleromystax barbatus egg increase as the female matures?
I ask because I have recently begun spawning the fish again and swear the eggs (and resultant fry) are significantly smaller than I remember them.
The female is quite young...hence; the question.

Kevin Korotev
Milwaukee

Post by **corybreed** » 21 Aug 2004, 00:59

Kevin,
I my experiences breeding S. barbatus the egg size has always been approximately 1.8 mm. I have bred barbatus ofall sizes and have not noticed any variation in egg size. I am curious about your question and wonder if others have had the same experince as you.

Mark

kkorotev · Post by **kkorotev** » 21 Aug 2004, 01:12

Mark,
Your 1.8mm reference is consistent with my memory. The eggs, which ARE FERTILE, are...maybe...75% of that.
I have always heard that there are two "strains/kinds/variants" of barbatus. Could this be an answer? Visually, I see no difference...BUT the size/age, which I've mentioned.
Kevin

fishnut2 · Post by **fishnut2** » 22 Aug 2004, 16:44

Hi Kevin,
I've been spawning barbatus for a few years now. The egg size has been consistent; regardless of the size, or age of the females. I feel that the size of the females will affect the number of eggs, not the size of the actual eggs laid (unless there's a very slight difference...I haven't noticed)
Hope this helps,
Rich

kkorotev · Post by **kkorotev** » 23 Aug 2004, 00:37

Well Rich...you're verifying what I already suspected which is good for my ego, but makes the mystery even harder to solve.
I think we need an expert's opinion. (No offense to anyone)
Where's Ian?

Kevin

Post by **Coryman** » 23 Aug 2004, 11:34

Looking back on my records, both my S. barbatus and S. kronei laid similar sized eggs, which measured 1,6 mm diameter. With some species I have seen a variation in egg size, and in some cases it has been quite considerable, but never with S. barbatus or S. kronei. I think the overall condition of the female will determine the egg number and size. Also egg size may vary slightly from one population to another.

It would be a good experiment to run two groups in parallel with different feeding regimes and see if there is any difference in egg size from the two groups.

Ian

Yann · Post by **Yann** » 23 Aug 2004, 13:26

Hi!

Egg size I beleive is related to food (quantitatively speaking) (quality has also something to do with it) and the overall population:
Let me explain:
Take for exemple the lions: when antilops are in good number, lioness will have more pupies... when the number of antilop decrease the number of pupies will also decrease...

I believe also that in a already much crowded tank with just sufficiant food for each individuals, the number of eggs will be rather low but their size should be bigger to give a better chance for the young, in opposite a small group with well enough food will , females will lay smaller eggs but more numerous...

That is the way I see it... and I observed it with Hypancistrus sp "Queen Arabesque" L260...

Certainly another factor could all mix this up: presence or not of a predator:

A survey with guppy was made along with Crenicichla saxatilis:
the results were in presence of this predator, males and females become faster mature, so the overall size of the population was slightly smaller in presence of this predator...

Cheers
Yann