Tank is 90 gallon FOWLR (and some mushroom corals) with 30 gallon sump with fuge chamber.
Current fish:
Pair of Ocellaris Clowns
1x One-Spot Foxface
1x Red Headed Solon Fairy Wrasse (aka: Tri-Color Wrasse)
1x Diamond Goby
1x Neon Cleaner Goby (I know that they, unfortunately, have a short lifespan, but I love the little guy)
1x Flame Angel
2x Cleaner Shrimp
Also: Large mixture of snails in DT + about 5 hermits in my fuge with the possibility of adding a strawberry crab in the future, just to eat any food/algae that winds up on the live rock rubble in there.
Intended purchases:
1x Green Mandarin - I'm just waiting to make sure my pod population is super-high before adding, but just to make sure; there won't be any issues between a dragonette and a diamond goby, correct?
tank maturity should be 9 months, otherwise fine
I've also been thinking about adding a McCosker's Wrasse - Would this be pushing it in terms of how many fish I'd be keeping (including the dragonette) in a 90 gallon? Also, would there be any issues between this species of Flasher Wrasse and my current (male) Red Headed Solon Fairy Wrasse?
C. solorensis can be aggressive so there may be an issue there
Do you think adding him would be an issue with my current Flame Angel? The Flame has been very shy and peaceful to my other fish since adding him, but he was my supposed to be my final addition besides the dragonette so

.
The issue is ecological niches. When you add a second fish in the same ecological niche, the tank needs to be larger so the fish's territorial imperative is not compromised.
Thank you!