4 week old fry

[azzakat]

I have 4 week old fry and over the last couple of days there has been 2 or 3 dead ones on the bottom of the tank each morning. They are showing no signs of illness all look fine water is good and clean all are eating well and parameters are fine they are just droping like fly's what could be the problem???

[samir]

treat them with formalin or prazi and then move them to a sterile tank