Hi I am a newbie to the marine world and would like to ask if I could put 2 manderine fish (unsure of sex) in my tank with my lawnmower blenny he is a very active boy and I was told that all three fish being rock dwellers and possible male could create problems. I am to new for to many problems lol. Please advise so I can let the seller know. She says its ok but then she has a very large tank. Mine is only 165 litre. Please allow for my spelling. Thanks Lesley