Hello and welcome to the forum.
First I have to say that this is completely wrong of which the way you're going about this. You cannot just go to a pet store and buy a pair of fish do a nights work of research and conclude that you're ready for it. Breeding is a huge responsibility and I'm sure you've heard this many times.
Hopefully you do MORE research and take my advise before breeding bettas. Double fin is not a correct term and niether is crown fin. It's DoubleTail and CrownTail. And the acronyms for those are DT and CT. Extremely basic betta info.
Anyway even though I will sort of school you on this, I'll answer your questions.
1) Yes. Any pair will breed. This doesn't mean any pair will have appealing fry (hopefully you know this is a term used for baby fish). Breeding a DT(DoubleTail) to a CT(Crowntail) will result in extremely messy fins as well as no doubletails in F1(first spawn). When I say messy fins, I really do mean messy fins with probably many deformities considering the DT gene carries deformities as it is. You will have some Combtails which are basically crowntails with extremely short ray extension. You will, also have CTs with longer ray extension, but bad finnage. And the overall form Is just not going I be very appealing, thus causing you to have all of these undesirable fry with no one wanting them. To be honest, no one in their right mind would by CTxDT fry. For pets yes, but even then people would go to their own pet stores to buy even better looking bettas than go through shipping and such.
2) The male doesn't have to build a bubblenest. Some males we're recorded to build the nest while spawning. Usually the male will make his nest after a day or so after seeing the female.
My advise to you is to keep them separate. Love and spoil them to the end of the world. Trust me, breeding them will only result in bad fins and fry with no homes. Even when giving them away, you really have a limited range of people willing to take them.
Breeding pet store fish will result in pet store fish and as I've said before no one will be willing to buy them. Trust me on this, I've tried it and it was not good. If you guys really want to breed, reasearch a lot more! IMO, you need it, just from you asking the simple question of "how long will it take for the male to start making his bubblenest?" shows me that you are not ready and didn't research enough to be ready to breed bettas. That is a question that is answered if researched correctly.
And the 'species' is betta splendens. You mean to say "what will the baby tail type be known as?" Tail types are much more different than the species.
When you know you're ready to breed, you can definitely answer these questions with a definite YES.
Do you have all the necessary equiptment to breed bettas?
-At least 5 heaters(for just one spawn)
-Grow our tanks
-50-100 jars for separating the males and some aggressive females
Do you have the space? Breeding bettas requires much space for grow out tanks and jars.
Do you have the time to breed bettas?
Do you have LIVE FOODS FOR THE FRY? Fry Need live foods to eat when they are about a week old and if they don't they will most likely die. Buying live foods like microworms, vinegar eels, bbs( baby brine shrimp) ect will help them to build their immune system and most importantly, GROW.
Do you have the money? Money plays a hug part in breeding and breeding bettas can drain your wallet if you don't know what your doing. Patience is key.
Do you have a quality pair? Breeding pet store quality is not suggested and not because the fish are bad to breed, but because pet store breeders will result in having too many fry with no homes. If you don't get a quality pair, you're looking at fish will no homes and an unsuccessful spawn. You'd also be putting more work on yourself than you should be starting on with. Buying a quality pair WILL be much more beneficial. From finances to seeing them go to nice homes. The finances are really to support the hobby in most cases.
Buying a really nice breeding quality pair will have fry that are very desirable and will sell. No breeder in their right mind will buy pet store fry from any breeder.
I'm not going to try to discourage you. This is just so you are aware of the requirements and needs if these fish. Especially when breeding.
I know you are doing this with the best intentions, but it really isn't the way to go. It takes the same money, effort, and time to breed pet store fish as it does to breed breeding quality fish.
Originally Posted by DoubleCrown
Me and my girlfriend went to pet co today and bought a Blue Female Crownfin and a Red/Blue Male Double Fin. when we got home and researched about bettas we saw that our female is ready to breed. so we looked up more information on breeding and got what we needed for it. and now i have a few questions.
1. will these 2 breed ok? and what will the baby species be known as?
2. how long will it take for the male to start making his bubble nest? (him and the female are in separate parts of the same tank with a clear divider and the female is ready to breed)