The effects of different diets on the survival, growth, food consumption, and conversion factor of juvenile red abalone (Haliotis rufescens) under tank culture conditions were investigated. The algae Macrocystis pyrifera, Gracilaria chilensis, and Sarcothalia crispata were administered as mixed diets, mono diets, or in rotation changing weekly. Additionally, an artificial pellet feed (ABfeed) was administered alone using a feeder or as part of a mixed diet. The experiment lasted 10 mo. The 100% S. crispata diet was suspended after 4mo due to low survival rates (92.1% ± 3.4%). Treatments had significant effects (P < 0.05) on survival, growth, food consumption, and conversion factor. The lowest survival rate was obtained using the artificial feed with a feeder (94.2% ± 4.3%) and the highest with a mix of M. pyrifera and artificial feed (99.0% ± 0.8%). The highest growth rates were obtained with the mix of M. pyrifera, G. chilensis, and artificial feed (0.044 ± 0.007 mm/day per 0.054 ± 0.005 g/day) and with 100% M. pyrifera (0.043 ± 0.002 mm/day per 0.054 ± 0.01 g/day). The lowest growth rates were obtained with 100% G. chilensis (0.026 ± 0.01 mm/day per 0.021 ± 0.01 g/day). Food conversion factor was highest with the mixed M. pyrifera (16.0) and G. chilensis (12.7) diet, whereas the lowest food conversions rates were obtained using artificial feed with a feeder (1.4) and artificial feed without a feeder (1.6). In this study, the M. pyrifera mono diet produced the highest growth rates in H. rufescens juveniles. Given that it is also the most abundant alga in terms of biomass and is easily managed during the feeding process, this would appear to be the best option for the culturing red abalone in southern Chile.