They are both peaceful shoalers and grow to the same size. But I doubt that they will actually school together. They will school among themselves and at times will swim with others who are in the same area, but are not going to actually school together to form a group of one. You should get more than three neon tetras IMO. At least a group of five... they would look much better schooling with each other. Same with the White Clouds.. I do not know what other tankmates are in that 29g tank, but they would look very nice in a larger group as well. So yes, IMO they can both be happy in the same tank together.

~ kate