Female and male bettas should only be kept in the same take for spawning purposes only, or if it is a divided tank. If they do spawn, there is a good chance that the male will kill the female. It's his way of protecting the nest. If they do spawn they can have anywhere from 300 to 500 fry, and the male juvinals eventually have to be put into seperate jars or some type of smallish container due to aggressiveness and fighting.
Raising betta fry is very time consuming and expencive as the fry need a large grow our tank (30-55 gallons), need to be fed twice daily and need frequent partial water changes. It is espically time consuming when it gets to the point that the males have to be seperated cause then you have anywhere from 100-300 jars to clean and change water in every day or every other day.

Male bettas should never be housed together either unless it too is a divided tank. They will fight to the death.

Right now you have a time bomb waiting to explode so my advice to you would be 1 of 2 things and I hope and pray that you will take into consideration one of these 2 options for the sake of the fish:

1. To get a divider as soon as possible and seperate them as he will just bully her to death, or she will bully him to death regardless whether they spawn or not.

2. Get a 2.5 gallon tank (the 2.5 gallon mimibows from walmart are perfect as they come with filter and lighted hood and are very reasonably priced) and put the male in that. The filter the mimibow comes with is fully adjustable and as male bettas can't cope with a strong current, turn it all the way down.

You can keep female bettas together, but they do best in a group of at least 6 so they can establish a pecking order (the alpha female picks on the next one down, that one picks on the next one down, etc....) That way no one female is bullied so much that it dies (but it can still happen). Heavily plant your 10 gallon tank, add a couple caves and get 5 more females, OR a small school of tetras, danios, white cloud mountain minnows, or other type of small, passive schooling fish. As long as it is nothing with brightly colered long fins such as guppies (the female may mistake them for a male betta and kill them), or is not very territorial they should be fine together.

One more piece of advice I have to offer. Please, please, please, when you get new fish, always take your fish store employees advice with a grain of salt. Most of them are part time, high school or college students, that have either been misinformed, or they just don't know. There are some good employees out there who do know what they are talking about, buy in my experience you have to look hard to find them. Take the time and do your own research on the net and find all the information that you can about them before buying them. It will save you and the fish a lot of unnecessary stress. Sorry this is so long, but I hope this helps. Good luck!

What about the kiddiepool idea?
Any advice there?

Actually, the kiddie pool idea could be pretty neat. You could try to set it up like one of their natural habitats, a rice paddy. It would be really hard to keep the water clear though due to the fact that you would have to put dirt on the bottom for the rice to grow in. They also live in slow moving streams in the wild so you could line the bottom and sides with river rocks, make rock formations into lots of caves for them to hide in, maybe put a small island with more caves, lots of live plants-fully aquatic and the ones that stick up out of the water for more hiding spots. You would have to try to pick a pool with no pictures or designs though as the ink used to make the designs might leach chemicles into the water and kill them all, or you could get a pond liner and put that in first. Depending on the size of the pool, you might be able to get away with keeping a few males and some females if it is a really big one, you would still have to be quite cautious and keep an eye on them to make sure no one is fighting or killing. You would just have to keep in mind that they are very territorial fish and will need some space to steak out their claims. Then you have to look at filtration and how strong of a current it would create, how to keep the water between 76-84 degrees F. If it's outdoors, how to keep preditors out of it, or bird doo, ect.... It would be quite a project, but probably a very rewarding one in the end. A great website for info on bettas is Betta Talk. If you go through with the pool idea, good luck. Like I said, I think it would be pretty cool, and would be pretty rewarding in the end if it works out.

Here is a link that might be useful: Betta talk

Although it would be nicer to set enough polyethylene liner fill an entire room up with cinderblocks and deck it out with houseplants and aquatics,I think i'll save that project for later on when it's more afordable.
I'm thinking I'll go with the kiddiepool idea first and see how that does.
My blackmoor goldfish would be so jealous.
They are being kept in a thirtytwo gallon trashcan i bought for them until i can get them a better living arrangement. Maybe i should get them their own kiddiepool. I'd like very much to breed them too once they become sexually mature. A whole pool of tiny blackmoors would be quite a sight to see!
Today I introduced the four i have to their new roommate.
A friend who had to move to chicago without much notice left me yet another male betta. It was being kept in a gallon jar with an amazon sword in it. There was a female in there not too long ago but he killed her. Knowing that the sword would be really handy for bubblenest construction I had to give it to my origional betta because he's busy courting the female. He's rebuilding his nest even now. I knew it wouldn't take him long. They love to build their nests under a broad leaf if they can. Waterlilies are perfect for this but the sword will do just fine. I'll get my hands on some lillies when I can.
Meanwhile the newer fella who was formerly in the jar has thirtytwo times the space in which to move around so he can't be too unhappy with his new digs even if the blackmoors unsettled him a bit when he first encountered them.

I wouldn't keep multiple bettas of mixed gender ANYWHERE together. Would you like to see what a group of females can do to a male? Check the link below.

I woul ddivide the 10G or give the girl her own space. Girls should be kept in odd-numbered groups, although people have had success with even numbers.

Here is a link that might be useful: Sorority Bettas Gone Psycho!

If your going to attempt breeding check for pH requirements. I am sure the cinder/concrete blocks are makeing your pH go off the charts. Sometimes concrete is used to make artificial reef rock or even in cichlid set ups. But it is "cured" for several months in fresh water to leech out high concentrations of calcium.

Wow!
Who knew my little pool should become such a den of murder and mayhem?
Should I isolate them to forbid breeding and forget about all this kiddiepool stuff?

Thanks for the heads up on the cinderblocks. i'd thought about that too. Would I be correct in assuming that the lime would bring the acidity of the water closer to neutral? Or am i way off here?

Asleep, you could do a pool of females, but you'd have to make sure they all get along or observe them closely. Otherwise, keep the males and the females separate, and the very aggressive females away from everyone else. Males of course should not be together at all.

I woder how log before they grow up and pose a threat to one another?
And what i'll do with them once they've matured for that matter.

I wonder what life is like back home in the rice paddies of thailand?

Concrete,limestone and marble (marble, a metamorphic rock, is actually limestone before being changed by the heat from molten lava) will buffer your water to a high pH. Certain fish like the high pH (african cichlids, brakish and salt water). Bettas can handle a certain amont of alkalinity I believe up to 8.0 ppm. The concrete will give you a pH of 9.9 or higher until cured which takes several months. A good substitution is Slate or Granite they do not alter pH up or down. Boil the rock for 15 minutes then cool it down with cold water before placeing it in the aquarium. Also another tip, only use true aquatic plants in your aquarium like the anacharis. Leting roots of non-aquatic or bog plants grow in the tank isn't a good idea. I know its done but usually ends up causeing more problems then not.

The roots of the terrestrials are in the gravel between the cinderblock and the aquarium's rear wall. Not at all like the peace lilly roots you see in those drugstore vase-plant-fish combos. Of course as mentioned earlier,I have anacharis and an amazon sword in there. Would you think that frequent partial water changes would be a way around the issue of ph increasing? I'm not too sure. So far i've seen no side effects. Everybody in there seems happy as can be. I would imagine if a betta were irritated from high alkalinity it would scratch itself on things like fish do when there's a high amonia content in their water. So far i've seen no such behavior.

A pH test kit could only answer that. I would suspect the pwc's would only help short term. As quick as over night the pH would buffer back up. Usually fish scrape on things when they have a parasite. Ammonia usually just stress them and causes loss of slime coat along with poisioning makeing them more suseptible to disease. To add Ammonia with a high pH is more lethal. I would loose the concrete. If the fish are fine and happy that is good. How long have they been in this tank.

They've been in there a few weeks now with no sign of discomfort whatsoever. Much as I hate the idea of losing the concrete I'm probably about to invest in the kiddiepool anyway so it shouldn't be a problem too much longer.

It rained alot last night and a good part of today. The tank flooded and the cuttings were completely submerged. I saw the pair exploring their newfound playground of pothos and other cuttings and it almost made me sad to have to bail out the excess water and force them out of the mysterious upper regions of the tank. I was looking at the male a few minutes ago and although i'm sure it's an overactive imagination on my part,i could swear he's staring up into the inaccessable reaches and longing to go back up there.
Tomorrow I am expecting to recieve a visit from my new landlord so that I can pay the deposite and get a new place to crash. I'm thinking it'll be the second bedroom that i assemble my indoor pool and garden in.

It won't be long now.
I can hardly wait!

I have been rasing bettas for a few years now in a half barrel setup outside during the warmer months here, which is uusally April to NOvember. I bring them inside when water temps drop.

I routinley let a male and female in the same 20 gal half barrel which is heavily planted with typical plants ofund in aquatic environments (lilys, iris, parrots feather, frog bit, duck weed, ribbon grasses etc) and the pairs alawys seem to work it out and have their own territory. HOwever once they do breed, I do remove the female and put her in another half barrel. I actually have three half barrels setup with a pump / filter in the lower one, that discharges water into the highest half barrel, which then spills into the middle barrel which spills into the lower barrel with filter and pump. The middle and lower barrels have very little to no surface disruption only at the point the spillway water enters the tub, and with lots of plants it creates a lot of still water areas. I do the breeding in the middle and lower barrels, and the females all reside in the upper barrel. What do I do with my young betta? I trade em for merchandise at the local pet store, and give em to friends, I have even released quite a few into my large natural pond, but even though I have found some from year to year, most probably become food for something higher up on the food chain or sucumb to cooler waters, but I can count on a few spawnings of them in the pond all without assistence or high mortality rates from year to year........

This will probably be the last year of putting any additional in the natural pond or possibly even raising them, as it just gets to be a lot of extra work involved. I feed them very very little in the half barrels, and once the fry need to be removed, I usualy remove the male temporarily until I can catch all the fry, and then repeat the process......I have a few 30 to 55 gal tanks as well as kiddie pools heavily planted and outside that I place the fry into eventually.

I took the tank inside yesterday because of the hurricane and when I studied the contents I noticed that there were dozens of tiny little fishies in there with the adults. It seems the pair has bred more than once judging by the fact that there are two different sizes of fry one slightly larger than the other. And to think that i don't even have them in a pool yet! I really need to get around to buying that thing.
In the meantime the youngsters are well hidden in the anacharis and don't seem to have any difficulty eluding their parents.