Guppy fin suddenly disappeared?

[tomsek68]

I hope that I chose the correct category, etc... Let me know, if I did something wrong.

I recently had to move all of my fish to my old, cube style 5gal tank (2 weeks ago, my 25 gal tank was damaged).

I had :
1 female betta
2 male bettas (one was fin-nipped before (and treated), not the one in the question now.)
1 tetra neon (will transfer him soon to a friend, to be with his kind)
2 cory catfish and a wood shrimp (previously the 5gal was exclusive to them)

Yes, the ratios are way off now. And horribly overstocked in this 5gal. I will buy a new tank as soon as I can afford it.


So:
This morning, I noticed that my orange/leopard tailed male betta's fin was slightly damaged. He had two 2mm horizontal "cuts". I found it odd, but he was moving like before. I bought him less than a month ago.
20 hours later, I noticed that he is dead. The color of his fins&body is completely gone, compared to his morning appearance.
Oddly, his fin is missing entirely.

What happened exactly? Thank you for your advice!

PS: The tank is planted heavily now. I did not see him during feedings.

 

[SaraB]

Are you talking about guppies or bettas? Your title and description are different.
If you are talking about bettas. He was killed by the other bettas. Males will fight to the death.
If you are talking about guppies, it may still have been a bullying issue.

 

[tomsek68]

Gosh, it was really late. Should have waited till morning to post. Guppies, all the way. It would be horrible to keep two male bettas next to each other. Especially if they would fight over one female. I'll modify the post, if I can.

So: 2 male and a female guppy

I had a male betta as a centerpiece in the bigger tank, and he is quite peaceful. Never had problems with him. He currently lives at a friend. I was afraid that he would kill everyone in such a small tank.

Can bullying cause the disappearance of a fin and colors in such a short period of time? And who might be the "main bully"?

 

[SaraB]

Ok that makes more sense. Yeah I still think he was bullied. I had a pair of female guppies kill a male before. There may not be enough hiding spots in a 5g.