I have a 240 gal display and my sandbed although pretty clean could use a little extra boost. I have a single diamond goby I’ve had for over a year and I was wondering if I could add 3 more? I know they tend to like to be in pairs, but as I’ve had this guy for a little while I’m not sure how well introducing more would go. I’d try to add 2 sleeper gobies too if that could be better.