title: A simple non-invasive method for measuring gross brain size in small live fish with semi-transparent heads.
abstract: This paper describes a non-invasive method for estimating gross brain size in small fish with semi-transparent heads, using system camera equipment. Macro-photographs were taken from above on backlit free-swimming fish undergoing light anaesthesia. From the photographs, the width of the optic tectum was measured. This measure (TeO-measure) correlates well with the width of the optic tectum as measured from out-dissected brains in both brown trout fry and zebrafish (Pearson r > 0.90). The TeO-measure also correlates well with overall brain wet weight in brown trout fry (r = 0.90), but less well for zebrafish (r = 0.79). A non-invasive measure makes it possible to quickly assess brain size from a large number of individuals, as well as repeatedly measuring brain size of live individuals allowing calculation of brain growth.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg , Gothenburg , Sweden.
authors.forename: Joacim
authors.initials: J
authors.lastname: Näslund
keywords: Brain measurement; Brown trout; Digital photography; Optic tectum; Zebrafish