Please identify! Killifish?
 

So this mystery fish appeared in an uninhabited planted tank a few weeks ago, and I though it was just a figment of my imagination, since nothing has been in here since some bolivian rams spawned almost 6 months ago. Just plants! All I've added to the tank since then, is moss from a shrimp tank, some blyxa japonica that was dipped in PP and H2O2, and some assassin snail babies.

So I'm thinking it must be a killie of some sort, or maybe something else. It looks a bit like my golden wonder killies, but they've never touched that tank (nor have I used a net between the two tanks.

So I went to take pictures of this mystery fish, and i moved a piece of java moss, and 5 of them shot out, they are VERY shy, and do not like their picture taken. Right now they are about 1-1.5cm, and they haven't grown much in the past few weeks.

Here is a picture of one that I got to stand still for half a second while I snapped one off:

Wow...it's very hard to tell, the fish being so small and translucent, however, the general body shape is that of a killifish. If I recall correctly, they spawn in plants.

Well, yes, some spawn in plants, and some in dirt. And the body shape/mouth look like killifish, but I'm really trippin out here. I have absolutely no idea how they could have gotten into my tank, unless they were transferred quite a while ago (6 months or more) and then waited to hatch until recently. And as far as I know, the plant spawners don't work like that, but the substrate spawners need a dry time, so I am so flummoxed.

I readily admit to very limited knowledge of killifish; I had a few species some 30 years ago, and at that time knew someone who specialized in them. Most of that has been forgotten, but I think that eggs laid in plants can survive months if kept moist, and that is how they are frequently stored and shipped.

Here is a killifish site with probably hundreds of photos (click on "pics" in the upper left) and info. With your fish at hand, you might be able to find them pictured here:

The International Killifish Association