> Has someone a threat to explain the dead of the fishes in my friends
> tank ?
There could be a million things. How were they handled between Gilbert's
house and getting them home? When was the last time he water changed his
fish tank? How long did he acclimate them to his tank? What are the
conditions in Gilbert's tanks? If you go from high water hardness (Ca,
Mg) to low that can kill them (even if you acclimatise them appropriately).
It could be some environmental thing in his tank. It is obviously not a
disease issue given how fast they died and the lack of symptoms (most
likely), but something environmental or stress related perhaps. That's my
best guess.
Cheers
Peter