Re: [Killietalk] Hatching Annuals and two fry per container

[Brian Watters <bwatters at shaw_ca>]

Bob Schwiegerath wrote:

>
> 2.   I can say (a bit off subject) that dividing annual fry such as Lp.
> peruensis into no more than 4 per 1.5 gallon tank for rearing has
> given me a
> reasonable sex ratio.  If I don't; I am heavy on males (:-(  .  (I know
> that this kinda'  flies against a study which appears in the latest
> JAKA but my experience is with only this fish
>

I don not have any direct evidence to support the suggestion that raising
one fry per container will, more often than not, result in a pair. However,
for what it is worth, I can relate the following experiences:

1. I frequently raise large batches of Nothos and, almost always, I get a
huge dominance of males. Even with batches of only moderate size, I still
get a dominance of males. For example, I recently hatched out a batch of 43
N. rubroreticulatus and raied every single fry which yielded 5 females and
38 males.

2. Whenever I raise only two or three fry (in the same container) I do,
"more often than not", end up with a pair or at least one of each sex.
Obviously, this does not work out every time but if there is not something
to this idea then I must be incredidibly lucky. Unfortunately, I have never
kept records of this sort of thing.

3. Perhaps more telling than the above, concerns my experiences with N.
ocellatus, the predatory Nothobranchius. Because of their aggressive and
predatory nature, I always separate the fry from one another within 24 hours
of hatching. This is to avoid having them try to eat each other. The fry are
then raised either in individual tanks or in large tanks (usually 15 gallon)
with dividers. Now, the main point here is that I have always had very even
sex ratios with this species or, perhaps, one average, a slightly higher
proportion of females. Given the consistent dominance of males that I get
when I raise even moderate sized batches of other Nothos in the same tank,
in my fish-room at least, getting even sex ratios is an anomaly.
Significantly, the only thing I do differently with N. ocellatus is to raise
the fry individually.
___________________________
Brian Watters
6141 Parkwood Drive
Nanaimo, BC, V9T 6A2
Canada
Ph: (250) 760-0564
E-mail: bwatters at shaw_ca


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