12'' st and 4'' ngt

I doubt that they would. What size tank are you putting them into? Do the two STs get along? I didn't have much luck keeping two similiar size dats together. It seems people can keep them in larger groups without too much problem. I had a huge dat that I tried so many different fish with and they ended up as expensive feeders. But 4 and 12 inches should be alright.

nah it wouldnt

The NGT will probably be ignored.

wow.

I would be looking to get a bigger tank

datnoids will not eat other datnoids whatever the size.
i have a 8" indo with a 1.5" silver. He wont even look at him.
in the past i kept my 10" STs with the mass amount of little 1" indos that were coming in and none of them ever got eaten.

That's good to know. It shows how they are not mindless.