i've had my betta now for over a year and a half , living contentedly in a 5 gallon tank all on his own (he seemed rather aggressive to have any friends) but recently i got two little corries and he has taken the intrusion quite well, occasionally he swam up and flared but seeing how ignored he was, he stopped.
however over the last couple of days he has taken to chasing the bigger of the two off if it comes too close to him but the other he dosen't seem to mind at all , in fact he seems to be 'protecting' it hovering over it, watching it eat, and keeping close by . can bettas become protective over another fish ? also scince i got the corries he spends alot more time on the bottom of the tank. bettas can be so weird!