so an update, I just realized the cause of Nick's aggression in the tank, as I saw his little breeding tube poking all the way out. He was in the mood for breeding, while the female wasn't. I got him back in his tank to prevent any hormonal breeding ques from stressing out the female who clearly wasn't ready, since I just moved her spawn and her previous mate only a few days ago. I've had bad experience with males wanting to breed with females who weren't in the mood for it, and I didn't want to take any chances, so I'll give my female a week or two of conditioning to see if she gets stuffed up with eggs again. Then hopefully I can try to pair them up again with a little more success.