Dead Bettas

A few months ago, I went on vacation. I had a gorgeous blue betta who
was seemingly happy and healthy--he'd been in my community tank for
about a year. I called to check on the fish (not talking to the fish
directly, of course) and was told that he had "disappeared." My niece
kept checking the tank for him, but found no sign. When I got home
weeks later, I also checked the tank. No betta.

A couple of weeks later, I bought myself a new Betta--a beautiful red
crown tail. Just before I put him in the tank, I pulled some
decorations to clean them--and there was the blue betta. Raw spots,
chewed looking, only able to swim tilted almost horizontal, and
trapped behind a decoration in the tank. I pulled him from the
community tank (a 30 gallon with some rummy nose tetras, corydoras,
glolights, and black tetras) and put him in a 2 gallon bowl with
substrate and a plant, where he survived until a few days ago.

Yesterday, my red crowntail was in fine form--gorgeous, active, eating
well. I saw him at about 7 pm and he looked great. I popped a movie
in the dvd player, curled up on the sofa, and, about a half hour into
Bourne Ultimatum, I looked over at the tank and there's my red
crowntail, trapped under a decoration (different one), just the trim
of his fins visible. I yanked the aquarium top off, moved the
decoration, but he was dead.

These decorations have been in place since I set up the tank. The
only fish who seem determined to get trapped are the bettas,
apparently. And they'd have to WORK to wriggle into these spots--the
crowntail would have had to shove himself under a decoration that is
worked into the substrate. The blue Betta would have had to wriggle
between decoration and glass into a space none of the other fish can
get into. Is this a typical Betta behavior? Because I'm about done
with bettas--I love having them, but they're so interactive and
attentive that I get really attached to them, which makes it very sad
when they die like this.

Any insight? My husband joked that the betta committed suicide, but
I'm not laughing. I take good care of my tank, the water's good,
things are clean, the fish are well fed without being overfed. Both
Bettas had built bubble nests in the past, so they must have been
somewhat happy. What am I doing wrong?

Kris