In terms of compatibility, peacock gobies are peaceful, so they will be happy with harlequin rasboras, and corydoras. As I said above, they like to be kep in pairs, so try to ensure that you get a pair. They are easy to tell the genders, the female has a pointed head, and a black line along the bottom of the anal fin. The male has a more bulbous head, and no black line.
They are easy to spawn, you need to provide them with "caves", I use small pieces of uPVC 3/4" pipe. Once they've spawned, the male guards the eggs, but once the eggs have hatched, they're on their own. They need conditioning with live food for this to happen, though.
When I was researching them, I found reports that they would only eat live food, not flake, mainly because they are too shy to want to go to the surface to feed. I feed Sera granulated food, which sinks easily, and my PGs feed off that quite happily, as well as veggies and live food.
