LF-apstasia eating critters

[Navarchus]

In my one experience not all peppermint will do the job. Once they realize there are other food sources in there, the same problem using cooperband for that job. The best biological solution for these hideous critters in a nudibranch called Berghia verrucicornis. They are a bit expensive and do so well in shipment so you should buy few of them.
Buy the way if you have any wrasses in your tank they will eat the Berghia verrucicornis.