all my fishes died overnite....

[greenwaters]

snif snif... i have a tank in my office, simple tank with
1)difformis,
2)java moss on a diftwood,
3)9 neon tetras,
4)4 rasbora,
5)1 corydorus,
6)1 SAE,
7)a dozen of shrimps...

DIY CO2 supply.. using overhead filter... tank is in normal aircon room has been ok for 6 mths with no deaths recorded... fishes all healthy. then this morning came n saw 2 tetras dead n a few others unstable.. suspected bad water quality so took out all the fishes and put them in separate tank with new water n few drops of blue medicine and salt. But thru out the day, 1 by 1 died till all wipe out. post mortem did not show anyting wrong abt the fishes... not tetra disease cos body not deformed. What happened? still mourning and in shock.... []

[budak]

IF you have been maintaining the tank well for the past 6 months, with regular water changes and it's not over-stocked (what's the size), the deaths point to some form of general poisoning. Something the cleaning lady used? Maybe someone tipped his cigarette, or worse, into the tank? Otherwise might be CO2 poisoning, esp if the fishes were gasping at the surface before dying. Did you check the pH for any major swings?

[DEA]

i would agree with budak
no reason for this to happen
most likely some accident happened and your fish suffered for it

[greenwaters]

the tank is normal 2ft so should not be over overstocked. Din check for pH swings though. The fishes were not gasping for air either...O2 from plants and from water agitation shd be enuf. To confest, i havn't taken care of the tank as well as before.... din do water change for over a month and then 2weeks ago did a 20%. CO2 oso stop during that month and then after the water change, i resume the CO2. But the deaths occurred not immediately after tat but more than a week later. Is the effect so slow? I tink external man-made poisoning can be ruled out cos the tank is under constant watch by me....

can fishes communicate and then decide to die together cos the tetras die together then the rasbora decided they wan to go and they oso commit suicide together but only after all the tetras died. Is the bond within species so strong?

[vinz]

Never seen tetras or rasboras exhibit lemming tendencies before. You will notice that for some schooling fishes, the school will either chase away sick individuals or the sick fishes will stay away from the school themselves.

Well, as for poisoning theory, you mean you stay in the office 24hrs? Anyway, even if someone innocently sprays insecticide nearby and the minute droplets settle on the surface, it can affect your fishes. Any overnight cleaners, or treatment of flooring, cleaning of upholstery, etc in your office recently?

Taking them out and putting them in new water with the blue stuff and salt could have stressed them out enough to push them over the edge even if they might have survived in the first place. Did you aerate the hospital tank?

Just tossing up possibilities.

[geoffrey]

What industry are you in? Could someone who has hands contaminated during work dipped into your tank?