zebras r pretty tuff from what ive researched,
and a pair is not the way to go...
u need a breeding colony of 6 or more of the fish,
preferably 2 males to 4 or 5 females,
u need a decent current and u have to angle the pvc or clay pots w/e u use for a breeding tube just right so that the water current helps bring clean water an oxygen to the eggs and not strong enough to where the eggs get pushed out,also the tube cant b to big it has to be small enough so that the father fish can block the entire entrance, and has to be big enough to where the mother an father fish can fit to breed and deposit the eggs...
and b4 all this u need to condition with tons of blood worms and simulate a a rainy season,
chk out planetcatfish.com its got all the info u need