I currently have a six line in my 90 ,I purchased him to combat the zoa eating nudibranches I had a few months ago and he did a great job at keeping them in check. I noticed a patch of zoos closed up this morning and I knew what that meant so I got the syringe out and pulled a monster one out. I was thinking of adding a second six line to the system but read mixed reviews online. And if they aren't good in pairs does anyone else have a fish they can suggest