Abstract: Personality is the constant intraspecific difference in animal behaviors. Energy metabolism provides energy for behavioral output. The relationship between energy expenditure and behavioral activities is still controversial. We investigated the correlation between standard metabolic rate (SMR) and personality, as well as the connection among different personality traits in a highly aggressive fish species, Macropodus opercularis. The results showed that there were significant inter-individual differences in behavior. SMR was positively correlated with the average velocity during measurements of spontaneous activity and aggressiveness, indicating that SMR can reflect the activity level of M. opercularis. However, SMR was not related to any other indicators of aggressiveness and boldness. It might be due to the more profound increase of SMR in lower social status individuals as the consequence of stress caused by intraspecific competition, which may obscure the relationship between SMR and most of personality traits. Our results suggested that the relationship between energy metabolism and personality in fish was quite complex, and that the weak correlation between SMR and personality in M. opercularis might be due to intense intraspecific competition.

Key words: standard metabolic rate, personality, Macropodus opercularis, inter-individual difference, correlation.