Guppy Died From Nipped Tail?

Does the guppy have tail rot? Or did my platys nip it? The guppy stays on the left and platys stay on the right. The guppy always stays near a corner but it’s probably because I got it a few days ago. Water parameters are 0/0/20. Ph is 7.6 and temperature is around 76.
edit:
He looks worse now so it must be nipping because fin rot can’t happen that fast right? What medicine should I use? I only have melafix. My lfs has a lot of types of fish medicine and it’s only 10 minutes from my house. Should I move it to my 10 gallon snail tank to treat it?

The guppy is now missing. I hope it hasn’t been killed/eaten. It could just be hiding but it hasn’t hid since I got it

 

What other fish are in the tank.

 

What other fish are in the tank.

Platys, bn pleco, opaline gourami. The opaline gourami is not aggressive at all

I just found the guppy dead. It couldn’t have died just from its tail being nipped right? It was swimming and eating normally. I didn’t see any injuries or anything either

 

My guppy that I got a few days had part of his tail nipped. I just did a water change yesterday to help with his tail healing. Today I saw that more of his tail was gone. A few minutes ago I found him dead. He was swimming, eating and pooping normally before. I’m not sure who could have nipped his fin. It was most likely one of my platys. My gourami is very peaceful and never attacked any other fish when I kept him with guppys. Or could it be fin rot? I don’t think it can happen that fast though

 

Yes, fish can die by being aggressively nipped. I've lost two fish this way; a male serpae tetra and a male platy. Each died after 2-3 days after initiation of attacks by "bully" male of same species. I was advised to solve this by either identifying the bully & eliminating it, or increasing the size of your community / school. With a larger school, the aggressive bully is less threatened and/or aggression is spread among a greater number of fish. In my case I chose to eliminate the bully male serpae tetra ( I only had 2 in my "school", so bully was the only one left). For my platy's, I chose to increase my school to 5, and currently have 1 male + 4 females. Good luck !

 

Only the tail was nipped. It died after a few hours. I have 3 platys. Maybe I’ll get 1-2 more. 2 of them still hide sometimes because they are new. The other new one chases the larger gourami so I’m thinking that one nipped it?

 

Adding to my prior post above....both my fish had their tails nipped, progressively shorter each day. Also, you need to consider the degree of stress this activity placed on the fish - stress is very unhealthy.

 

This happened in one day. So you think stress from being moved to a new tank then being nipped killed it?