I have a pair of Snowflakes that are 100% fish and coral safe but not invert safe. Thats not to say all snowflakes will be the same. Both have and will snack on shrimp, and my smaller of the two has unsuccessfully gone after the hermits on occasion.
One is full grown, the other is about half my larger ones size. The smaller of the two seems to misbehave(more active, and actually seems to actively hunt for inverts) more than the larger one, so i dont think age/size has anything to do with it. The larger one stays in its pvc tube 90% of the time.
The fish i have kept with them that could potentially be in danger are a yellow watchman goby, mandarin, yellow corris wrasse, mottled clingfish and chromis pretty much since day one with them. No issues, and often both eels touch skin to skin with the watchman goby.
Zebras are reported to be the most reef safe, hunting only very specific inverts, and i would love to have one, but they get very large. I will definitely get one though when i finish the down stairs remodel in a couple years and install the large peninsula i have planned. I thought about one for the 300g stock pond, but i know i would come home to an eel on the concrete floor at one point or another.
IMO Golden dwarfs are not invert OR fish safe. They are one of the more notorious fish hunters out of the eels commonly described as "reef" safe. They do stay relatively small, but bite size fish can be on the menu. If you don't have smaller fish then its not an issue.
None are 100% "reef" safe, because none are 100% invert safe. The Zebra is likely the most reef safe however, but again, they do get large. I would not keep any in a "small" tank, with the exception of possible the golden dwarf, but i dont know what your idea of small is so...