Exploding fish

Vogel, Andreas vogel at ubaclu.unibas.ch
Wed Sep 10 13:03:50 EST 1997

James Mohler wrote:

> week in our zebrafish cultures.  Occasionally the dead fish
> are eviscerated, their abdomens apparently exploded.  I am curious
> whether yeast carry-over from the Drosophila larvae we feed
> thme might be the culprit.
maybe, maybe not. we frequently see senior fish balooning in our stocks,
and even though we _do_ feed them with drosophila larvae, i don't think
that gas is the reason. if it were, the fish would have a hard time
swimming anywhere but at the surface of the tank (which they don't). i
find it more likely that they have a kidney problem. fish are hypertonic
compared to the water surrounding them, so water "osmoses" into them
continuously. to get rid of the water, the kidneys produce very dilute
urine; if they don't, the body cavity fills up with fluid, the fish
baloon and eventually blow up. the lack of intestines in the bodies can
safely be attributed to cannibalism.

> We are growing the Drosophila larvae in potato flake-live yeast
> media.  We suspend the media with 3rd instar larvae in 20% sucrose
> to float the larvae (residual potato clumps sink), skim off the larvae,
> then collect the larvae by filtration through cheesecloth.
we do it basically the same way, except we grow the larvae in corn food
w/ yeast and collect them from ??% glycerin, and then freeze them.
drosophila are fed 1x per week, and i've heard more can cause health
problems due to an oversupply of cystein.

> Having been told by my mother not to eat raw bread dough, because
> your stomach might explode (which I thought of as an old wives
> tale), I've got to wonder whether this might be the problem (I've
> heard that gas in sheep is often lethal as well).  Could our
> larvae preparation be the problem?
btw, cyprinids don't have stomachs.
i hope i could help a little to point to the source of your problem. 
good luck in saving your fish

Andreas M. Vogel                        Phone: +41 61 267 2064
Abt. Zellbiologie                       Fax: +41 61 267 2064
Biozentrum der Universitat
Klingelbergstr. 70
CH-4056 Basel

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