I need a knowledgeable answer

[Tyler777]

Few days ago I lost 4 yellow/black pand mollies no sign of being attacked or being sick. The day before they died theumywere all swimming together happily ever after the next day the 4 of them were dead.
A couple of days later I lost my swordtail boy n one of his females. Then I lost 2 platties. All of them happy the day bfore then I found em dead . Even if I have a bully I don't know how come it always attacks the same species n if I had a infection or illness how come attacks the same species n not everyone.
I had a spike of nitrites in that tank but even so again attacking all members of the same species.

Anybody went through something like that or know anything bout this weird situation ?

 

[CassCats]

What is your pH, GH, and KH

All of the species you listed need very high parameters. Hard, hard water. Softer water will reduce their ability to fend off problems and are often the first to have problems if there's a problem in the tank.

 

[Tyler777]

What is your pH, GH, and KH

All of the species you listed need very high parameters. Hard, hard water. Softer water will reduce their ability to fend off problems and are often the first to have problems if there's a problem in the tank.

I will test the tank tomorrow n get the parameters