There's honestly quite a few ways to make SRT, at the end of the day tho the main thing ya need is a Texas or Carpintis which ya already have. Now as for the other half you can use blood parrot, kkp, red devil, midas, red shock veija, rose queen, SRM FH's or a high red FH of a different strain. The main thing will be culling out the undesirable fry from the desirable ones, doesn't really matter what ya try to cross it except when it comes to BP's. BP males are "almost always" infertile so if your Texas is female I wouldn't even bother trying to get a BP.
The main reason most ppl don't use midas and red devil's is just due to their wide range of color compaired to the other fish species. It just means even more culling with those 2 to produce results. Granted if ya already got 30 red devil's I would try with those first, just pick out the brightest reds and hope ya get one of the opposite gender to your Texas.
P.s. ya should probably vent your Texas to be 100% certain what gender it is before ya start trying to find it a mate, makes it much easier/cheaper in the end if ya know what gender ya have vs what gender ya need. Also don't be surprised if it just refuses to mix breed either, can't really force a fish to love another.
