Will my betta forget about my other fish?

I have a 15 gallon tank with my female betta in. I also have 3 adult female guppies in there and 8-10 fry which are a month or so old (these are in a breeder net together). Yesterday i chose my biggest fry which was 2-3 months old and put him in the main tank with my females but my female betta killed him. This isn't the first time she's been aggressive, shes shredded tails before etc. Anyway, my plan is to put all my guppies AND fry together into the new tank i have (cycled of course) and wait a while. In 2-5 months time when the fry are adults and strong, i would really like to add my female betta in there. Would she have forgotten about them and would she be kind/peaceful once again like she was when i got her from the pet store? I don't really want to keep her in the current tank as it is in an annoying place in my house AND it isnt the best for her (it's loud, old and barely any gravel and very few plants, and no air stones unlike my other tank).

 

Its not really about forgetting fish, its more about your bettas personality. I would not, given the fact that she has killed and damaged other fish. If she has done this twice already then I honestly would keep her alone in her own tank, the first time alone was already a sign that she just isn't fit to live with other fish.

 

Fish don't quite work like that. Sure it will forget them, but that has nothing to do with her aggression towards them or any other fish.
When i kept a male with a herom of females, i used guppies to keep everyone peaceful and diatracted and it worked well, but i did it with the understanding the guppies served as food.

 

Its not really about forgetting fish, its more about your bettas personality. I would not, given the fact that she has killed and damaged other fish. If she has done this twice already then I honestly would keep her alone in her own tank, the first time alone was already a sign that she just isn't fit to live with other fish.

yeh i agree, she chose the weakest fish and leaves the others alone. I really hate her living in the current tank though but i suppose it's better for all of them. At the store she lived in an overstocked sorority tank with no plants etc, and she loved peacefully with my guppies for 5 months before she switched.

 

My beta was in a 10 gal with guppies and Cory's they were fine for a while but then I started finding dead guppies I checked everything and couldn't figure out what was going on but one morning I turned on the light and found my beta attacking my Cory's so I moved her to a 5 gallon heavy planted tank with a ghost shrimp and she's fine she even let's the ghost shrimp take food from her.

 

As bettas get older their personalities will change. Most often they get ‘grouchier’ so a fish that was peaceful and friendly towards other fish before may become aggressive and attack its tankmates it’s lived with for awhile.
If she has killed or damaged other fish in the aquarium you really should separate her from them.