"bad eggs" fish disease?

[Freek van Eeden]

We recently got something in our aquarium which is really 
frightening me. I was wondering whether there is anyone who has 
some experience with the potential disease described below.  

We have some fish which are laying eggs but the eggs turn bad 
through epiboly, if they aren't dead the next day they usually are 
extremely retarded/reduced and show overall necrosis. Only an 
occasional embryo develops normally. Obviously we thought that 
one of the media/incubators we are using were bad so we 
systematically tested this. However, it turned out that it was fish 
specific. Embryos of one cross were o.k. under all tested 
conditions whereas the other cross gave the described phenotype 
under all conditions. Several fish from different origins show this 
effect, whereas other fish (swimming in water from the same 
system) don't show the phenotype (yet).  

Therefore I'm afraid that it may be contagious

My guess would be that the eggs are infected with some 
aggressive bacterium or mould.  Of course I am very afraid to loose 
precious fish, has anyone ever heard reports of such a disease? 
Are there antibiotics that can be used to test whether it is an 
infection?  

Thanks for any help or advice
Freek
--
Dr F. van Eeden
freek at niob.knaw.nl
Hubrecht lab./NIOB
Uppsalalaan 8 3584CT Utrecht
The Netherlands
0031 30 2121800