This is one of my favorite fish...I think they have beautiful coloration.
This is from my own experience.
They are definitely Golden Wonder Killifish, as the above post stated, they are great jumpers...you need to have the aquarium completely covered. It looks like you have a male and female. They do better in larger schools and the male will continuously try to mate...maybe to the point of being too much for 1 female.
I always keep 1 male per 5 female. And it is better to have only 1 or 2 males as they do tend to chase each other.
They are omnivores and scatter egg layers.
I believe they are very peaceful, mine never bothered any tank mates
They get around 3 inches and are not the species that have a live span of 1 year.
Mine always mate when well fed, I have eggs all the time. When I first got mine, I kept some of the eggs to hatch. It was a disaster...the fry are cannibals and will eat their smaller siblings. Mine had to be housed in individual containers if I want to keep them. Once they reached about 3/4 to 1 inch, they did not eat each other and were peaceful.
I assumed they must have a strong survival instinct to be mean babies.
I hoped this helped.