I just bought a few fish for different tanks. Both tanks are stable and were not new tanks. One fish I had was swollen with babies. But then I woke up the next morning and the one male I had a while was dead.[ when he was fine the night before] and the fish wasn't seemingly pregnant no more. I don't know if there are babies as I looked and couldn't find any. If she aborted them..how would I know and what does she do to abort them?

I assume we are talking about guppies, the death is a mystery ????? unless more tests are done, but yes they can abort, one of mine aborted in a bare tank I just managed to see them, they were not fully formed and just looked like very tiny glass beads would be difficult to spot in a furnished tank, could be various reasons why, stress, conditions not right, harassed by other fish !!!

Yeah, Soon as I let her in some of the males were all over her. I felt really bad too about it. I also never knew fish can abort there own young. I hope it doesn't happen again its kinda depressing. I do regular tank changes and keep the temp to there liking. PH and everything else seemed right on so I believe fishy attention got the best of her. Oh..and the other male that died was being..."Probed" by the other male..At first I was like..okay he likes males. Then he was dead by morning.

any babies/aborted young will be immediately eaten by the other fish, best to isolate any pregnant females