DNA fingerprinting has proven to be an extremely powerful tool for the identification of individuals and pedigrees. Here we report that the Jeffreys' 33.6 and 33.15 multilocus probes produce complex yet informative DNA fingerprints in tilapia, Oreochromis niloticus. With the exception of one anomalous fragment, presumably the result of mutation in the tandem array, each hypervariable fragment in the fingerprint could be attributed to one or other of the parents, thereby indicating Mendelian inheritance of these loci. The results of these studies suggest applications in aquaculture genetics including assessment of inbreeding rates, as genetic markers to identify individuals and family groups, and the labelling of broodstocks to secure ownership of property.