At the moment my 15 gallon tank only has small shoaling fish living in it, but for some time I've been wanting to add more as the tank looks so lovely and it's sad to have so few fish in it. I'd really like to get a female betta (or even a few of them, if that would be possible) but I'm a bit worried about whether my tank would be suitable for that. These are the reasons:
1) One time I had a female betta living in a smaller separate tank next to my 15 gallon one. I decided to put her into the main tank at short notice and she jumped out a day or two later. I think this was just because of the shock of being suddenly plunged into a much larger and completely different environment with different water parameters, which I really shouldn't have done. But it still worries me.
2) I've kept female bettas before but only in unfiltered tanks. Although the filtration is very gentle in my main tank, it might still be too strong for a small betta. I have a big thing about not subjecting fish to currents that force them to struggle against it, especially if they're new arrivals.
3) I have some glowlight tetras and cherry barbs. They're my only fish at the moment. I used to have 8 tetras and 4 barbs and they were incredibly agressive and nipped each other constantly. A few jumped out of the tank from the stress and since the numbers have been reduced to 5 and 3 they are very peaceful and never fight. I'd really like to have more small shoaling fish - they're so cute. But I'm worried introducing new ones might upset the established hierachy. And of course I'm worried that adding a betta might do the same thing. It would be terrible if the tetras nipped the betta's fins!
So I need some advice. Do you think my tank would be suitable for a female betta and if so could I have more than one? (I really, really like bettas

)