I used to think that bettas cannot be crossbred with other anabantoids, but I later found that could be wrong.
It would be interesting if somebody cross paradise fish with betta to extract good gene from paradise fish. Paradise fish have tough scales and powerful hit.
wild-caught paradise fish fight
I followed all the reports of betta crossbreeding with other species. Here's what I collected.
1) Many years ago, a person from Canada posted on Malaysian Betta Yahoo club that he was able to breed bettas x paradise and have eggs but didn't hatch.
2) A member on Vietnamese forum claimed that he cross-bred them when he was a schoolboy. The eggs hatch but his father dumped them when they were a few day-old b/c of his poor schoolwork. He added that in order to get them to breed, there's a trick. He used male betta and female paradise fish b/c the eggs will float and survive . If male paradise x female betta, eggs sink and male paradise will not be able to collect them . His writing seemed honest though, so I believe him.
3) I found this answer in ultimatebettas.com forum
Hybrids are still considered "taboo" in the betta breeding world, but I am seeing them pop up more so maybe that attitude will change..... what dogsnfish said is true "...if you aren't willing to put years into it....then you might be better off working with something else... Also, don't let people know what you are doing if you are trying to attain a new strain.....copy cats would arise. Just my opinion." I will not post pictures. Sorry, just try to google it and see what comes up.
If you really want to do something new you will need the dedication to follow it through. About 5 years ago I started experimenting with bettas and blue paradise fish. Me and a breeder in Georgia met and exchanged ideas and stock,
we recorded and documented our fish and did several experiments over the next couple of months, hybridizing paradise fish and splendens..... the result............ well......... very ugly fish......... lol....... did our experiment work.... ya.....
We scrapped the project after 10 months and decided not to pursue it any longer. We had done what we set out to do.... so what im saying is if you want to do this keep it a secret in your fish room................ lol...........
4) Bettas maybe able to crossbred with croaking gourami.
An senior player from Vietnam suggested that if good female fighter is not obtainable, one can start the fighting line from crossbreeding a good fighter with a female croaking gourami. Later, various forum members confirmed that they did the cross out of curiosity but the baby grew up very ugly and shy so they didn't pursue the project .
Many people argue that croaking gourami are very wild and shy, not good in fighting but other claims different. One person put a bamboo strainer underneath the nest of croaking gourami in a ditch and put a male betta (don't know if it was a fighting line) in. The gourami made a quick attack without much flaring . Very strong and fast, after a few hit, the betta ran . He said croaking gourami made powerful hit and accurate compared to bettas.
If crossing paradise fish to fighting line, using black paradise Macropodus spechti or M. erythropterus is probably better since the black paradise are known to be more aggressive than the more common M. opercularis. The body look more stout and big mouth .