Many coral reef fishes exhibit unique reproductive strategies that can play a central role in conservation programs. Cardinalfishes (f. Apogonidae) are all paternal mouthbrooders, where the male holds the fertilised eggs in his mouth until they hatch. Males may fertilise the eggs of multiple females resulting in polygyny and skewed reproductive success. Here we present 23 tetranucleotide microsatellite loci in four multiplexes to identify breeding strategies in the Pyjama cardinalfish, Sphaeramia nematoptera (Bleeker, 1856). All markers were polymorphic with a mean of 14.39 ± 1.61 SE alleles per locus and an average observed heterozygosity of 0.624 ± 0.054 SE across 384 genotyped individuals. This marker set provides a rare opportunity to investigate mating behaviour, reproductive success, kin group structure and larval dispersal in natural populations of a coral reef fish targeted by the aquarium trade.