[Zbrafish] Spawning problems

[G. Koumoundouros]

Hello to everybody,
for the last 3 months we face significant problems with the spawning of 
our fish. This is a problem that occasionally appears to our facilities, 
without been possible to be explained.

This time, due to a malfunction or the RO water hardness elevated to 
almost 30 odH and ph to 8,4. Could this be a reason why we face this 
problem?

Has anyone noticed any periodicity in the zebrafish spawning?

Any help is appreciated

Thanks in advance

Giorgos