since i put them in one has a slighlty more purple belly, and has become VERY aggresive, to the other fish(more so the african butt. cichlids) and even to the other krib....
i dont think its a good idea to put two pairs in a 30g. i had 2 pairs in my 55g and it just didnt work. here's a recent thread you can look over for some more info/experiences: