Artwork created by the incredibly talented Guangjian Huang.
I would link back to the page this was taken from, i.e; the image source. So if this was from a page off deviantart, I'd link it to the gallery page (not the direct image link).
Homeworld:
No known homeworld, thought to have always been amidst the stars. Certain sectors are charted more than others for their existence. Some Merlusian even choose to live in asteroid belts.
I'm not trained and well-versed in the ways of the codex, but you're probably better off giving a vague asteroid or some kind of source point as their "home" world. Or say they originated in X system, or the Y Sector, or something like that. Something to give someone an idea of where they might have came from, as submissions are (generally) done from an OOC, informative, perspective. Like when you make a submission to the factory, you don't say the manufacturer is a secret, you have to list it for judgement purposes.
On the flip side, you can say they no longer remain in their original location, or that it was destroyed.
This is just my personal opinion, whether you go with it or not is up to you.
ICily, the length of life in unknown. Many believe them to be immortal. That said, the Merlusian live to be around 10,000 years old, and do in fact die. Not many Merlusians will ever make it to old age though, and those that do are very weak. The cycle of maturity is like this:
Infancy 1-50. In this stage, the Mer is in a egg and is growing.
Childhood 50-150. The first sentient moments in their life, is what for most species would be about 1-10 years old.
'Teenage' years 150-500. A long period of time, 10-19 in what most species live, is spent discovering and is for most the most curious times of life.
Adulthood 500-7,000. The largest gap of their life, spent doing whatever they choose to do. Most die in this time.
Seniority 7,000- 10,000. No Merlusian has ever been documented to live past 10,000 years of age, and this is considered to be when the body dies.
From a biological standpoint, and again my opinion, this is really, really, long. I wouldn't suggest giving them anywhere near that lifespan. I am aware Anzats and such other illusive species have long life spans, nearing 500, assuming they actually live to die naturally, but I would drastically reduce this. I, personally, wouldn't be opposed to a long lifespan of maybe 200-300 years, just based on my current skim of the sub for the species, but 10,000 is a very, very, long time to biologically persist.