The objective of this study was to examine the association between brain iron measurements of monoamine function and behavioural measurements of learning and memory. Male hybrid tilapiasOreochromis aureus × Oreochromis niloticuswere fed either an iron‐deficient (ID) diet or an iron‐adequate (IA) diet for 8 weeks. TheIDfishes showed significantly lower iron content in brain and decreasing learning and memory capacity. The fishes that showed increased learning and memory capacity had higher levels of iron and monoamine oxidase activity in brain. In addition, the results showed that learning and memory behaviours were related to monoamine (dopamine and noradrenaline) concentration in the brain. This suggests that iron can enhance learning and memory capacity in fishes and that the effect may have monoaminergic mediation in discrimination learning and memory tasks. The experimental data suggest that the properties and neural basis of learning and memory of teleosts are notably similar to those of land vertebrates.