Chris,
I just returned from a diving trip to Bonaire as well. I saw Cherubfish on at least two seperate dives, only in the shallows. I'll try to recall as much as I can about the second sighting.
Dive site: Windsock
15 to 20 feet of water
3 or 4 Cherubfish darting in and out of cover provided by round branch like pieces of coral rubble on the sand. Extremely shy and active little fish.
Not far from there an octopus had hidden in similar rubble. You could only see his eye and maybe a tentacle or two.
This and other rubble zones had an abundance of what may have been Bridled Goby (Coryphopterus glaucofraenum) [p 279, Reef Fish Identification Florida Caribbean Bahamas, Paul Humann & Ned Deloach, Enlarged 3rd Edition] Basically small sand colored gobies that were constantly darting around on the sand and low rubble.
Not far from the Cherubfish was a brain coral about the size of a large cantaloupe. Situated on the coral were two yellow cleaner gobies (probably Sharknose Goby, Gobiosoma evelynae, p 267, Ibid; but could have been some other cleaning goby with two yellow stripes.
The area was also crawling with nudibranchs (lettuce?). Not sure what kind, but once you saw one, you saw twenty in a square yard.
There were other fish in the same area as the Cherubfish, but I can't recall what they were. So much to see, it's hard to remember it all.
All of this was at roughly the same depth, and no more that 20 feet apart.
Just noticed your post above about the Bridled Goby. My reference doen't have a entry on the Sand Goby, so I can't say if that was a better match to what I saw. It does however say that the Bridled Goby appears tranparent and unmarked in sandy areas, but marked in grassy and rocky areas.
Good luck with you biotope. One thing this trip taught me is that even a small piece of the ocean is a big piece.
Cheers,
Chad
