Different Rainbows Schooling

[Weiro792]

So I have 6 blue eye fork tail rainbows and  5 thread fin rainbows, all of which school together. 
 
I was just wondering if this is typical behavior. 
 
Also I have a bit of an issue with the male to female ratio of my forktail rainbows. I have 5 males and 1 female as this is all they had at my lfs. Should I consider quarantining the female? Or just observe their behavior closely?

 

[daizeUK]

These fish are happier in bigger schools (preferably at least 10 fish per species) so they are schooling together to pool their numbers for safety.
 
Forktails and threadfins are not the best choice of tankmates as the forktails are more boisterous than the more delicate threadfins.  This was the advice I got from a specialist rainbowfish site when I was considering getting some forktails for my threadfin tank.
 
Similar to you, my original stocking was 7 threadfin males and only 1 female.  The poor female died within 26 hours.  I think it must be very stressful to be the only female in a tank of males.

 

[Weiro792]

Thats what I figured about them schooling together. I was actually planning on having about 8 of each once I sell off some of my peacock gudgeons.
 
I have also noticed that the fork tails are more active than the thread fins but it doesn't seem to bother the thread fins. I'm wondering why they're not advised to be together.
 
Thanks for the advice. Yeah I have 4 females and 1 male of the thread fins... I'm planning on getting another male soon. I enjoy the sparring that you see between the males. Not sure what to do about the ratio of fork tails as that is what the vendor sent my lfs when I special ordered them.

 

[daizeUK]

The advice about choosing tankmates carefully is because threadfins are slow fish and very delicate eaters.  They have tiny mouths and I've noticed that my threadfins will only accept the tiniest morsels.  They are easily outcompeted for food by faster moving species so make sure that they are getting enough to eat.  They may be stressed by more energetic tankmates.