The happy couple!

[Kabong]

Bachelor #1 was a red firefish about the same size as the purple.
Red #1 didn't even make it 24Hrs
They were in a 20Gal QT

From researching on RC the info I came up with was.
-They are very hard to sex
-Purples are the most aggressive of the "firefish"
-Firefish will generally school with others until sexual maturity.
-Once sexual maturity is reached they pair off, occasionally a male will pair 2 females.
-In a large enough tank it's possible to keep same sex's, But their will be aggression to wards each other.
-Firefish won't generally tolerate other members of there on species.

and one of the most humorous things i came across was a story of someone going to there LFS wanting a pair of helfrich firefish and the employee telling them the best way to get that was to buy 5 of them and they'd just kill each other off until you were left with a mated pair. Averaging at least $150 each thats like $750 a pair.