So... it's kind of hard to determine, but the spotted silver hatchet fish I mentioned i believe is the 'maculatus'.
That would then be
Gasteropelecus maculatus. I have never seen this species locally, and I believe it is rather rare in the hobby. It is similar to
G. sternicla which is more often encountered, and both species can attain more than 3 inches in length. Not as delicate as the
Carnegiella species. All species need a group of course, and I have found larger groups much better to calm the fish, and with the
Carnegiella species this is very essential (larger groups, 9+). Which leads me to the comments on jumping.
Thought they might not if I have a lot of foliage at the top. Maybe I'll pass on them. And I do have glass canopies I could use, but- I have plants growing out of my tank and I tend to keep it like that.
Uncovered tanks are not advisable with any of the hatchetfishes, regardless of floating plants. Carnegiella species need open surface, which can be achieved with some floating plants leaving spaces. As for the other species, that remain under the surface rather than on it, I have observed that they will only remain under open surface, not under surface plants, when given the options.
Jumping is generally a fright response. If the fish are startled by something below them--which is why tankmates must be so carefully selected--they tend to jump to escape the "danger." And this tends to occur more during darkness. Over the years I have lost several hatchetfish during the night; a couple of times I neglected to fully close the cover glass after feeding, and I usually find this out in the morning when I discover one or sometimes two dried hatchetfish on the floor. The species in Carnegiella seem more prone to jumping in my experience. I had my marbles (a group of 15) in my 115g a few years back, and three or four times found a hatchetfish caught between the glass panes of the cover in the morning. I still can't imagine how this happened, given the miniscule opening between the panes, but it did. I now have the group in another tank with no losses.
So a tank cover that leaves basically no openings is necessary, or I would not consider hatchetfish. Most fish can jump if it comes to that, but the ability to leave the water and glide--they have been proven not to "fly" by beating the pectoral fins so the incredible thrust they can achieve propels them from the water with considerable force--for several feet must be kept in mind.
Byron.