Half my fish died last night

[snorvich]

is the tank drilled or running off canisters? have seen non drilled tanks wiped out after they were topped off too high, which led to no surface agitation, and that led to a lack of 02 in the tank..very sorry for your losses and know that pain all too well...good luck, tk

Good thinking. Had not occurred to me.

 

[Mache62]

stray voltage is a good possibility if you can rule out any local aerosolized toxins....try checking with a meter

 

[humaguy]

stray voltage is a good possibility if you can rule out any local aerosolized toxins....try checking with a meter

have never seen stray voltage only wipe out part of a tank...