Neon tetras

Hi All,

Sorry this is my first post I'll be as accurate as I can.

I currently have a bio-orb 60 L tank which has a male fighting fish and 4 Neons.

Last night there was a problem with my filter and had to turn the power to it off although my heater was fine and stayed on.

I have awoken this morning to find 3 of the neons dead at the bottom of the tank and 1 missing - assuming its been ate.

The fish were introduced over a couple hour period yesterday.

The water seems fine as the fighter is still alive and swimming around well but with the deaths and disapearance of the tetras i'm starting to think something might be causing the issue.

When I purchased the fish the gentleman in the store said there should be no problem introducing these type of fish together.

Please help.