So I've had my three golden wonder killifish for a little bit now and they've been doing good from the start. Had a little ick problem but it was taken care of quickly and they have turned into pickier eaters (they wont eat most of the food I give them now but they sure will grab my catfish's food ahd swim around with it before they realize its too big).
I have one male and two females and I figured thats probablly a good thing since most fish are a 1:2-3 ratio but I've been noticing some aggression. My male chases both the females - one more than the other and her fins are starting to get a little torn up, the other female even chases her now. The other one the male chases a little but she stays near him. The male and female will check out my cories and chase the pandas until my peppered cory shows up (he's still a tad bigger than my male killi). I'm mostly worried about my little girl - she's the one that when I come home and turn on the leds she comes out and just stays there looking at me and following me (I sneak her baby shrimp when the two are at the other side of the tank

).
I can't take anyone back to the store since I got them because the store didn't want them. I also can't get more for the same reason. Both my 10g tanks are a bit overstocked (1-2 inches) and the 5g I was using at a qt is now home to my betta. I am looking for a used 55g but there is no telling when and if I'll get it.
Is there anything I can do to at least dumb down the aggression? I was thinking maybe I could move her into my tetra tank? I know I'll have to do extra water changes but is that even an option to try til her fins are at least better?
Oh, and if I do manage to get the 55g I want - will the added space break it up or do I really need to look into trying to find some more? (Its too cold to ship and any car rides will be up to at least 2hours one way.)