Re: NANFA-- The demise of my red shiners

Pete Liptrot (
Tue, 21 May 2002 19:21:55 +0100

> One thought is that they are all males and they have all been in full
mating colors for three > months.

What is the normal length of the reproductive season in this species?
It could be that the extended time that they have been in breeding condition
has severely impacted their immune system (there is plenty of evidence that
elevated levels of testosterone has a deleterious effect on the immune
response, particularly I would imagine in spp. that usually have a distinct
breeding season).
The presence of multiple males will also probably have been a significant
stressor without the need for actual physical damage to occur.
So they might simply have 'burnt out'.
This can happen with European Minnows (Phoxinus), and I've seen it happen to
male Sticklebacks. As far as tropical fish are concerned you will also find
that in the case of Loricariid species that usually show reproductive
reseasonality, males will quite literally hump themselves to death in a
constant cycle of spawning and brood care with no R&R, given enough ripe
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