What is wrong with my platy?

[memeaquarist]

I have a black - tailed platy in my 20 gal community tank.

He has always seemed healthy until now, I noticed him sleeping all the time or just laying in the floor.

It looks like he is dead, but he is not, since if I poke the glass a little he moves a little and then lays down again.

It's really weird, this morning he was swimming perfectly. I have no clue what could be wrong.

I did notice my zebra danio nipping him last week, but it has seemed to stop. Could it be that he has trouble swimming? This happened some days ago with my guppy, he was a victim of fin nipping and wasn't able to swim and one hour later he died... I hope it's not the same situation. It was so sudden!

Please help!

 

[Autumnsky]

What are your water parameters

First thing is to do is test the water and then a pwc. If no liquid test kit, then do a pwc 30%, then another 30% back to back one right after the other. This back to back allows the change in water to be less stressful for the fish.

Save a water sample BEFORE you change the water to take to the store if you don't have a test kit. And one after to compare.