neon tail rot

[joestoys]

i notice my neon tetra tail rot.... or looks like get nip off but the rest of my fishes are ok??? so what's wrong????

they are still happily swimming, eating, chasing one another....

[PeterGwee]

Is it a newly setup tank? Check your water parameters... If possible take out the infected fish and put inside a quarantine tank..with necessary hiding places and treat with salt or medication. Then pray for the fish...