The Clown Goby just sits there, if you like that sort of thing. A good article, "Let's Clown Around..." is here:
http://reefkeeping.com/issues/2002-10/hcs3/index.htm
The Court Jester/Rainfordi's I've had were reclusive and didn't do well, perhaps because they like thicker fields of Hair Algae and my tanks typically have enough snails to keep algae mowed down to invisible nubs. Besides, the Bicolor already claims every spot of algae in the entire 28. I would not add a Koumansetta rainfordi.
If some kind of funny fish (clown, court jester
) is wanted, why not add two small mates for the lone clownfish. A Reef Oasis has many clownfish from which to choose. Older clownfish readily accept any number of young clownfish and eventually choose one for a mate, at which time the rejected clownfish(es) can be removed from the top back corner where it/they are cowering out of respect for the new pair.
While we're in the Damsel family(clownfish are damsels) have you thought about a Yellow Tail Blue Damsel or two? Peaceful, very active and hardy, these are great fish for any size aquarium. If a child is in your home, a YT Blue Damsel can be their "Dori".
The Dottybacks are beautiful but will aggressively take over and defend new territory, the entire 28 gals.
On the other hand if, like me, you like the purple/yellow color combo, the Royal Gramma is beautiful, peaceful and a far better choice than the Bicolor Dottyback, IMO.
I can confidently say that almost any small Wrasse is a great choice. I love the Six-line's green tail and horizontal red stripes, but stay away from the other "lined" Wrasses because they may eventually eat Hermits and Shrimp. I assume there is a Peppermint Shrimp in this tank. If not, I would recommend adding one. The Six-line Wrasse is beautiful, active and usually very peaceful. It is also utilitarian in that it eats little pests, like unwanted flatworms and bad bugs, along with good bugs of course. There are a great many Wrasses from which to choose. The Flasher Wrasse are gorgeous. After initially wiping out the bug population, a Wrasse needs to be fed well with supplemental frozen shrimp. Also, more snails will need to be added to the aquarium to keep algae in check that was previously eaten by the bugs.
Scott Michael is a great fish book author. We've had him here as a guest speaker. Have you seen his book:
The 101 Best Nano-Reef Species: How to Choose & Keep Hardy, Brilliant, Fascinating Species Perfect for Small Aquariums It's $11.99 at Amazon Kindle ($13.22 paperback) or maybe someone here could share their copy.
Hope this short writing helps a little.
Aloha,
Mark
Edited by Mark Peterson - May 09 2016 at 6:42am