Hi bro, though fairy wrasse is considered non aggressive but chasing might be expected and if the new wrasse cannot take it, it will die. Get a bigger size one, acclimatize them, train them to eat like pig, place them in Betta box to allow seeing and once aggression lessen, possible to release. Master wrasse, bro rogertt did mention to use mirror trick. I once got one wrasse trying to whack my new wrasse, once open the betta box, the wrasse went in and trapped it and release the new wrasse, few days later, release it and everything was fine but still encounter occasion chasing. Do cover yr tank as they are jumper . Cheers.