Hi Lilia, i don't know special mating behaviour of A. cruzi but i think it shouldn't be too much different to other apistos. Healthy food with some variation is important (living food is optimal - if not available fed baby brine shrimps) to get in the mood. Good signs are: * turning to breeding coloration (yellow/black) * sticking to one (!) cave * enhanced defending of her territory to other fish (in your case: chasing the tetras around) * female showing belly and waiting for the male to follow to the cave (in that case it should be almost done) Most of that won't be shown in the absense of a male - give them a reunion and a try after a week.Things can be forced by water changes and raising temperature to 27°C, lowering of hardness and pH (if to high). Maybe someone who has got experiences with cruzi is able to help. Good luck Thomas