They are about 3 inches. Unfortunately, last week I found my female stuck on my maxi-jet. I thought she was going to make it and she was eating fine for a few days but yesterday she died. So now I just have 3 males. The males are doing well though. I added 2 T5HO lights a couple of weeks ago and put coral in the tank. I have a lot of aiptasia and I am trying to get some Berghia nudis to eat them. I plan on bothering a couple of people soon to see if I can get a female or 2 .