Everyone else basically nailed it on the head, but I'm going to review one more time for you.
Conditioning bettas is like a UFC fighter getting into shape. He eats high protein food, drinks lots of clean water, exercises frequently, and begins to get into his peak physical condition. Similarly, bettas in preparation of spawning need to go through the same thing- lots of top quality foods like mosquito larvae, daphnia, bloodworms and brine shrimp (has to be adult brine shrimp as adult bettas won't pay attention to tiny baby brine shrimp) CLEAN clean water every day heated to 82 degrees, plenty of room for swimming and moving around in the tank. Don't let the pair see one another, EXCEPT for a few times a day for only a matter of minutes. This peaks their interest. Keep this up for a minimum of two weeks, and you will see your male become more vibrant in color and your female swell with eggs. It will almost look like she is bloated, but not to the extreme. You male will also most likely be started on a bubble nest.
For your Betta fry, I would acquire a micrworm culture on top of your bbs and infusoria. Microworms are very easy to maintain- all you have to do is make oatmeal every few weeks, and starter cultures are dirt cheap. In fact, I believe MrV is selling MW cultures (forgive me if I'm mistaken, V.)
Next, I do not recommend an undergravel filter. The bottoms of your tanks should be bare to begin with so that they can easily find fallen foods. Placing the filter in the open water will certainly suck up your fry. Keep them in the spawning tank for at least the first 3 weeks and use a turkey baster to suck up uneaten food and waste from the bottom of the tank. Moving them into a full 20 gallon at such a young age will most certainly kill them. They are extremely fragile and sensitive to their environment at this point. When they get big enough to handle a sponge filter, put them in the 20 gallon that is filled half-way, then add more water each week until you eventually have a full tank.
Alright, now let's talk genetics. I'm assuming you got these two from your local pet store, correct? (EDIT: Okay, so the male is from a petstore. xD Apologies, you guys were posting while I was typing.) That means that their DNA is extremely jumbled and scrambled, for the sole purpose of giving the customers a variety to pick from, and overall quick sales. You probably don't think this is such a bad thing, because all you want at this point is a successful spawn. Right? Well, you should probably stop and think for a moment. Bettas can produce well over 1000 fry in one spawn. Let's say Lady Luck is watching over you on this one, and you have a 80% survival rate. That leaves you with 800 betta fish that are store-quality, essentially the same exact quality as the fish sitting at the pet store right now. Ask me this- how long do you think it would take the petstore to sell 800 Betta fish from their shelves? Even with the hundreds of customers they get each and every day? Probably a very VERY long time. That means that you are in the same situation, potentially worse because you probably don't have hundreds of friends that can come strolling by your house every day. This means you need to be prepared to provide proper housing, heating, feeding and filtration for 800 fish. Not only this, but a way to separate every single male. As far as selling bettas on Aquabid, no breeder in their right mind would ever buy a pet store bred Betta with no genetic background. Take a look under the "veil tail" section and note how few there are, and how cheap they are selling. On top of the regular price, you'd be asking people to pay shipping as well. Why would they, for a poor quality fish?
Doesn't sound like a whole lot of fun, does it? The BEST way to avoid getting yourself into a situation like this is to begin your breeding hobby with quality fish with STABLE genetics. Fish that you are able to know the "pedigree" of. You also need to look into culling, and understand that it is a big part of Betta breeding and reproducing only the best of the offspring. The combination of these two will allow you to more successfully sell your fish to breeders who desire the traits you are recreating. Through this you are improving the foundation of the betta splendens society- and that makes you feel all warm and fuzzy inside!
In the end it is well worth it to invest in higher quality fish, because it gives you more flexibility in line breeding as well as selling your stock. It can take a lifetime to sort out the negative genes of a pet store fish- for example, long anal fins, unclean scales, short ventrals, red and blue wash and poor conformation.
Like I said before, even though genetics don't seem like a big deal to you right now, starting out right can save you a world of hurt down the road.
Last edited by KadenJames; 04-26-2012 at 12:34 AM.