VT & CT is something you really don't want to do if you're looking for pretty fins in your fry.
You will end us with a mess basically of some ct's some vt's and vt's fins that looks shredded.
Many people here will discourage you from breeding petstore bettas because you will not be able to sell them, they will be hard to give away and you might find yourself with the only option of giving them to a LPS IF they accept them.
IMO, if you're spending so much money (I'm talking hundreds!) and effort on breeding and raising bettas then why not start with the best pair you can afford?
Personally, I wanted to jump in and breed my petstore bettas when I got into betta keeping but after all the research and kowing I didn't know my betta's genetics, I started looking for fish from an extablished line.
Anyway, I'm just saying this because it's something you might want to take in consideration before breeding. Really up to you!
Youll get VTs and depending on how many rays your CT has you may get low grade deltas. Since CT is partially dominant, the amount of webbing reduction will vary but most likey you wont get much , just little raggy tips at the ends, not not a full CT.
Correct, CT's are partially dominant while the VT gene is all dominant. People saying that the offspring will become combtails is just the worst guess someone would say, something closest to that is a VT with some combtail webbing at the end; ugly. Most of the of the offspring will be just buzz cut VT's, or ragged tips like what trilobite said. The best choice for you right now if you want to breed is get a male CT, there's alot out there right now. ;)
You'll get veiltails with the combtail type edges. A combtail is anything not CT crossed to a CT(fish with partial web reduction) so it's not/wrong/ to call it that.
It's just that most consider combtails do be the delta and superdelta kind(and combtail halfmoons are called halfsuns).
if i remeber the pictures right your girl does look cambodian but it was really blury. She might color up more as she grows older, hard to tell untill she does.
As for not being able to sell petstore bred bettas, that's not true. I've bred petstore bettas and sold the better of the fry. it's just that yo'll have a hard time selling Vailtails.
I would reccomend a different male for your girl. ^^ a HMPK or a CT. A few people are looking to breed towards better CTPKfinnage and would probably buy combtails who carried the shortail gene to save them doing the first step. If you could find a cambodian boy or a red boy you'd get some cute babies. ^^
DT being double tail?
Hmm, i know they give extended dorsal...the CT will still only be partially dominant. if the ct carries dt you'd find dt's in the spawn if not you'll just get combtails that are DT geno(well...most anyway).