Please help

[cashley0328]

I have a 120 gallon cycled community freshwater tank. I am not sure what is going on. Within the last 5 days I have had no less than 15 fish die. I have a local guy that maintains my tank. He owns an aquarium store. He recently did a routine maintenance and brought me a few new fish. I have treated with seachem metaplex. Nothing seems to be helping. Every morning more
And more fish are dead. Some have red spot on them. Some nothing. Last night I have a Cory that was laying upside down. He was on his way out. Red spots and bloated belly (see attached photo). I have added salt, increased tank temperature, a couple of partial water changes. All parameters are within normal limits. Please help. I am at a loss

 

[Autumnsky]

It is possible that the last cleaning caused a loss of beneficial bacterial in the filter media.

Or the fish added caused illness in the others.

Do you have a test kit? Know what the parameters are?

Were any cleaners or spray used near the tank around the time this started?

I would contact the maintenance person right away.

How is it going with the fish now?