Is it ok to house different species of firefish together?
Unfortunately, there is no definitive answer for that. In a long tank, where there can be two different territories, it can work. A six foot tank is not a clear situation, but I would guess probably not. If you still want to try, introduce the new ones on the opposite side of the tank. Firefish have a small territory and if there is no perceived overlap, it may work.
Currently have 2- Nemateleotris magnifica (guessing a m/f combo, they stay together-no fighting)
Time will tell. If you have exceeded a year, then you have a bonded pair, which eventually may mate if they perceive you have a friendly environment.
Would love to add 2-(M/F) - Nemateleotris decora
Just love the personalities of the firefish.
So do I. One of my favorites
Tank is a 125g 6ft tank. Community fish & shrimp & snails