These guys are 3" and 2".I have them in a 120g 5' tank with an rbta,these were the first additions.I just added 2 wrasse and the female took exception chasing them down if they got anyway close to the nem,I can see this being a problem as I start to stock the tank in the long term,my question is would a 25 g jbj aio 18 x18 work for this pair I know GSM can get to 6".