[Zbrafish] Sex-Bias & low production

[Judy Bennett]

Hi All,

We've been experiencing decreased egg production in one of our fish 
facilities.  It has stalled some experiments and we're looking for ways to 
get the fish back on track.  We do use a mass mating system for our WT 
lines and those tanks have been producing consistently, although we don't 
know how many of the males are doing the fertilization.

I have not seen any problems with our water quality, and two other 
facilities using the same feed have been doing fine (ZIRC recipe).  At the 
moment I have increased the water exchange, am going to try a new dry feed 
and have increased the amount of brine shrimp we feed out (although I'm 
worried about overfeeding at the same time).  The PI thinks it correlates 
to the female sex bias in the facility- leaving us with fewer males that 
may not be potent.  He is interested in bringing in a male bias line to see 
if it will help the problem.

-Could bringing in a male-bias line help and/or does anyone have fish they 
could possibly send?
-Is there a guideline for the amount of brine shrimp to feed per a certain 
number of adult fish
(X mls/1000fish)?
-I also suspect a certain amount of inbreeding, but haven't found any 
information about when it could start to affect gonad development/spawning.

Thanks for any help/information you can offer.

Judy Bennett
UMass Amherst