Your post reminded me of a conversation I had a few years ago on this subject. Hopefully this will be of some use to you.
I can give you some info... it relates to the Purple Firefish (Nemateleotris decora), however I'm sure the same applies to Orange Firefish (Nemateleotris magnifica).
The reference is below:
Schiller, Guenter, Spawning Behavior of the Decorated Firefish, 1990, SeaScope, Volume 7, Fall 1990. Aquarium Systems, Mentor, OH, 44060, ISSN 1045-3520.
In the above article, the author references his experience with N. magnifica too (see "Fish Views and News, January 1977, Desert Aquatist Society).
SeaScope is thankfully available online, so you can access the article under the Breeding/Propagation header:
http://www.instantocean.com/Ocean-of-Knowledge/SeaScope/SeaScope-Index-by-Subject.aspx
How you'll get a hold of the other reference from 1977 is beyond me!
Finally, a bit to follow up on N. decora breeding reports:
http://aquadaily.com/2009/02/09/purple-firefish-faq/
Best of luck and please give an update!
ChemLife