bettas are weird like that. i had a zebra danio nip a full grown betta and it died as a result (indirect though, it got fungal fin rot). a young betta just killed my GLO-fish (genetically modifified zebra danio). it chased it and it would have been fine since the danio was much faster, but the danio got stuck and the betta was beating it for hours until i found it. it died that night.
moss doesnt float. unless its not really moss. i have used duckweed, riccia, hornwort, and floating wisteria in my betta breeding tank; the betta didnt care. except it couldnt nest under the hornwort. actually, they seem to be fond of floating leaves of nymphae lillies. i had one that would always nest under the floating leaves of a banana plant.
That's sad :[
I had a reverse of that story, a while back when I was setting up a 10g small community tank [since it was all I had room for at the time] I had started with 4 zebras, i've never had problems with them in community tanks, nor my father, or any friends, so I like to start all my communities with them.
So a few weeks pass as I introduce more fish, some Neon Tetras, one of my female bettas, and then I took my fish out temp, moved stuff around, and put them back in, plus two other female bettas that had been acclimateing to the tank.
The females checked each other out a bti, shoaled some, and hung out mostly in a corner together for the first day.
Watched them for a few hours, they eventually claimed their own corners and that was that, everyone was happy.
Next morning I wake up to my zebras chaseing around my purple and black CT female, but I couldn't see my pink delta female, but that wasn't my biggest concern at the time.
By time I got my females out [which was only a few seconds, I had to find the net I knocked over in my rush] the female was dead.
I got my original female out, after finding her hiding inside one of my smaller plants, but she had a huge open sore on her head and her body was bloated, when I went to get her out of the plant she freaked and darted out, and the zebras cornered her and started biteing again, got her out in time [she died a few days later of internal bleeding].
Started hunting for my pink delta, in hopes she too was hideing someplace.
She was. Dead. :/
similiar wounds. All while I was hunting for her, the zebras were attacking my hand o.o
It was crazy. After I got the bodies out they seemed to calm down some, but were still very agressive towards anything alive.
I'm now thinking it was them that killed off my Neon T.s, too.
So I gave them to my father to help cycle his already cycling tank. They were eratic in swiming, and were all over the tank , rather then towards the top, even when they were with other fish.
When my father got three Angels for said 20g, the angels seemed to put the zebs in their place, and now they're placid again, skimming the top, and non-agressive against people/fish. Hell, I was surprised they weren't attacking the glass, let alone other fish.
I guess any fish can be a little nutso, lol.