The effect of feeding four diatom diets (Amphora sp., Navicula ramosissima, Amphora sp. + N. ramosissima, and mixed diatoms) and two attachment substrates (PP+CCA: polyvinyl plates with crustose coralline algae; PP-CCA: polyvinyl plates without crustose coralline algae) were determined for seed production of abalone, Haliois asinina. On day 5, significantly higher number of larvae settled on PP+CCA fed with mixed diatoms followed by Amphora sp., N. ramosissima, Amphora sp. + N. ramosissima, and abalone larvae reared on PP-CCA fied with N. ramosissima only. Fewer larvae settled on PP-CCA fed with Amphora + N. ramosissima, Amphora sp. and mixed diatoms. The size of abalone juveniles from PP-CCA was significantly bigger compared with juveniles measured from PP+CCA. However, the number of juveniles harvested from tanks provided with PP+CCA was higher compared with tanks with PP-CCA. This study has shown that crustose coralline algae favored the settlement of H. asinina larvae and inoculation of diatom slurry is necessary to provide sufficient food for the growing larvae.