[Zbrafish] Re: Juveniles and adults with open gills!

Tyrone via zbrafish%40net.bio.net (by tgenade from gmail.com)
Fri Apr 15 03:02:48 EST 2011


On Mar 29, 4:51 pm, Vishal <vsaxe... from gmail.com> wrote:

> I am seeing many adult and juvenile zebrafish in my facility with open
> gills. I am not sure either the gill operculum is broken or head is
> deformed in a way that we can see gills from outside! Is there anyone

Three environmental causes typical of high density fish rearing
(ranked from most to least likely):

1. Ammonia levels. Levels of 0.05 ppb can be toxic and cause
deformities. This value is from
http://www.amazon.com/Fish-Invertebrate-Culture-Management-Systems/dp/047102306X
Chapter 7 somewhere. (Can effect anywhere from a handful to most of
the fry.)

2. Vitamin C/D deficiency. As Vit A is implicated in a lot of
developmental work it could also be involved. (Effects the smaller
fish more than the larger ones.)

3. Intestinal worms/parasites. Add 30 mg 10% Flubendazole to 1 g of
food and feed for a week and then another week 3 weeks later. (This
can cause almost every single fish to be deformed.)

Advice: lower fish density, improved filtration/water turnover and a
better diet. If the food has been left exposed to light or moisture
for any length of time the vitamin content will have been degraded.

I am reluctant to jump to "genetic" causes for the simple reason that
most lab strains are already very inbred and you would thus expect to
see these deformities is most fish, not just "many". The environmental
problems above tend to cause random deformaties which would affect
many fish.

Best of luck solving the problem.



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