"Patience is the key to success" ....
1. How big/old are they? IMO adequate size is 3.5 cm and above.
2. No v bars means she isn't ready. You must isolate her and try flaring her once in a while. Don't show her any males at the moment. Use other females or mirrors. When she is aggressive against the other/mirror like she's saying "I'm gonna kill ya", try floating her again with the male. If she dances (or flaring) with the male and showing vertical bars, She is ready. Wait 2 - 3 days then release her.
3. Use a lot of live plants so the female can run and hide. She will be bitten. This is normal. Some males beat females half to death while others may not touch them. So If you have done the above, there's nothing you can do about the aggression.