Popeye sea goblins is indeed one of the common names for
Inimicus sp. stingfish. The most common species in the trade is
I. dactylus.
IMHO, they're super interesting fish, altho if you're looking for a lot of motion, stingfish aren't for you. They're good eaters and aren't terribly tuff to wean onto dead foods.
Inimicus spend most of their time buried up to their eyes/snout where they lie in wait for tasty prey to venture within striking range. When out and about, these fish usually "walk" around on their dactyls (the modified pectoral rays that look like legs).
If you're a fan of the weird and wild, this is a perfect fish, and IMHO, is one of the "must haves" for any scorp collection.
One final word, these fish are just down a notch from stonefish in terms of toxicity, so getting stung will be pretty painful, altho not fatal. Don't worry tho, these fish are VERY easy-going as long as you don't fit into their mouths.
We keep
I. didactylus,
I. japonicus, and
Chorydactylus multibarbus stingfish, so if you have any specifics questions, ask away.
Here's some inspiration: