A
Anonymous
Guest
I have NEVER had problems introducing two cleaners (you added the same species, L. amboinensis, right?) together...that's so odd that it killed the other one. If you try again, maybe try with two small ones at the same time. They're hermaphroditic, so there shouldn't be any 'male vs. male' type aggression. Any cleaner can mate with any other cleaner, basically, and usually they're happy to do so.