Aggressive fat fish at dinner time

Thanks for the help. How do you tell the sex of danios? Could her "gut"
be eggs? I don't plan on breeding them right now, but do I need to do
anything to help/protect her? Also, I do have one fish that has the
clamped top and bottom fins. But he has been like that since I got him.
He schools and interacts with the others, and he is really active at
dinner time, but most of the time he just chills in different areas of
the tank. Should I do anything, or is he just a depressive fish? Thanks
for the advice.

Travis