Jackass penguin chicks from the age of about 10 days were hand reared on different diets: mullet Liza richardsoni, anchovy Engraulis capensis and squid Loligo reynaudi, until they fledged. The weight of food fed and the daily weight increment of the chicks was measured. Excreta were collected every 5–6 days and analysed to establish metabolized energy and metabolic efficiency. Culmen measurements were taken regularly and plotted against age. The age, weight and sum of food fed up to fledging was compared between diets as well as with field data. Compensatory growth was exhibited when stunted chicks on a relatively poor diet had their diet changed to a relatively better diet.