My Monos just do some light chasing after each other. I bought them the size of nickles...they are 3-4 inches across now. I have four but for my 125, I wish I just had one. They grow really fast and are good at eating pellet foods. You need a big tank for these guys. They are harmless with my other fish and inverts.

Love this Mono Fish! He is so beautiful and such an interesting personality! He doesn't bother anyone and has actually become friends with our yellow wrasse! They swim attached at the hip looking for food! He is a very mellow swimmer who loves swimming through the rock work to find new caves. He is a little hard to feed when competing with quicker eaters, I let a couple pellets sink in front of him and sink a few spirulina flakes! I highly recommend him, he is sweet, beautiful, and easy!