Sounds doable to me.
Although I don't keep many of those particular fish, so I can't say how any of them will get along in a 40b.
That will all depend on the particular fish and your scape.
I will say that I currently have 8 fish in a 40b, including a small tomini tang. And it is completely fine, nutrient wise.
I had 5 fish in my 40b for the longest time and nutrients (N03 & PO4) would constantly bottom out and my corals would suffer... I always had to dose nitrates or my corals would RTN when nutrients hit zero. So I decided to add a few more fish. I QT'd 3 more fish, added them and now several months later, my nutrients are still bottomed out. Adding 3 more fish to my 40b had little effect on my N03 & P04 levels. now they just bottom out slightly slower.
This is my test results from last night.
That's with 8 fish in a 40b.
I currently have;
2 picasso clowns
2 anthias (female Randall, female Carrberryi)
2 damsels (regular blue cyanea, and a springerri)
1 Royal Gramma
1 Tomini Tang
My fish are pigs and I feed heavily. I feed my fish at least 3-4 meals per day, all frozen foods.
Even with that fish bioload, my nutrients still bottom out without regular dosing, just not quite as often now. instead of having to dose nitrates weekly, now I have to dose them monthly.
My fish all get along great, but none are aggressive either. The Royal Gramma is probably the most aggressive, but really it's just protective of it's cave. it does not chase other fish around, just away from the entrance to it's cave. Even my 2 damsels are mellow. There was some chasing the first week or two, when fish #6 - #8 were added, but that subsided pretty quick and everybody settled in. It helps if you can shake the rockscape up a bit. Move something or add a new cave or two. Without a spot to hide/retreat too, the higher fish numbers won't work.
If nutrients are rising, then you aren't exporting enough. 8 to 10 fish shouldn't be an issue with the amount of live rock/sand and filtration you can get in a 40b. My 40b doesn't even have a sump, nor a refugium. Just a lot of live rock, sand, and a big butt skimmer.
I'd also recommend you add the fish in groups, rather than individually. Fish feel safety in numbers.
A group of new fish will do better than a single new fish... They get picked on less and feel less stress when they have a few fish to hang around with. Add one new fish and all the existing fish attack it and it doesn't have anywhere to go and they can get stressed bad. Add a group of new fish and they can hang out together and the aggression from new tank mates is divided amongst the new fish. if you are going for 10 fish, I'd add them in groups and move the rockscape each time you add a new group. You could hold off on placing of any corals permanently until you have all the fish added and final rockscape determined.
Also, with that many fish in a smaller tank, I highly recommend you fully QT them all, otherwise you will probably have constant ich outbreaks in such a tank if you let the parasites in. I don't think you'll ever get 10 fish into a 40b that haven't been quarantined.
All of my fish have been fully QT'd, either by myself or Dr. Reef. I would recommend you do the same if you really want to get 10 fish in your 40b.
QT the fish in groups, add the fish in groups, move some rocks around, and filter/export heavy.
good luck!
