Hey Bongo Shrimp! I'm going to *guess* that the species of cardinalfish you have is
Apogon margaritophorus? I've seen this species called "Copper" Cardinalfish before (but not "Copperband") as well as Lattice Cardinalfish and a couple other common names.
If in fact it's
Apogon margaritophrous, I've actually spawned the fish many times myself, but could never get to the point of having larvae. They have large spawns (several hundred small eggs) and tiny larvae that spend a considerable amount of time in a pelagic phase.
Sadly, the Banggai Cardinalfish (
Pterapogon kauderni) is atypical among cardinalfish..it is one of only a couple species that feature "direct development" of their larvae. Most Cardinalfish have much larger spawns, much smaller eggs, and much shorter incubation times (i.e.
Apogon margaritophorus might only incubate 7 days based on my experiences).
Most of these other Cardinalfish can be reared with enough effort, but they are much more difficult than Banggais, and much more difficult than easier species with a pelagic larval phase (like Clownfish). They will require dedicated rearing tanks, photoplankton and rotifers. Adding in copepod nauplii to their larval diet will help a lot.