That's a lot of fish for a 40. Especially if the clowns are of the variety that get big and the coral beauty grows to full size. Do you have a large sump?
For me, I wouldn't say so.
I run 8 fish in my 50 cube -- 3 wrasse, a Sunburst Anthias, 3 gobies, and an Assessor and have absolutely no issues. They all are very social and mingle together well, they also never fight over territory, and a few of them like to sleep together. My assessor snuggles up with my Neon Goby some nights, my Tangaroa sleeps with my FireFish, the wrasse all have their own spot but my lunate sleeps with a flame shrimp.
I think in this hobby, the more the better. Equipment is so good these days there's almost no concern for water quality to be an issue.
In the reef, a lot of fish are visually communal, meaning if they look out from the rocks and don't see a bunch of other fish going about their day, they're gonna hide. It's just how fish work, in fresh water and salt water -- When the fish aren't there, they're hiding from a predator, otherwise the reef is bustling (or the lake/river) with a TON of activity. I've found that more fish lead to a healthier and happier system.
Something huge in Fresh Water are using "Dither Fish", the term means
"The term dither fish refers to an arbitrary group of aquarium fish used by cichlid-keeping aquarists to reduce innate timidity in some species". So I decided to try and slightly modify the technique in my tank by most overstocking instead of a cloud of tiny fish. And to my surprise, not only is everything more outgoing, but everything is less likely to fight -- More fish = more spread out aggression. This is also typical of fresh water setups. It's typical to use a smaller fish to keep the larger fish more active and outgoing.
A lake, river, and ocean are all vastly different places. But animals are innately similar. Dogs from all corners of the earth know what a belly rub is, I'd imagine fish have some similar traits.
