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Growth variability in 23 mensural characters was examined in 387 specimens of stone loach, Barbatula barbatula, from England. The standard length (SL) of the specimens ranged from 15.3 to 115.4 mm. We tested the hypothesis that body proportions change abruptly, rather than gradually, at certain intervals of ontogeny by fitting linear, quadratic and split linear curves to plots of each variable against SL. Based on patterns of allometric growth, two groups and two subgroups of mensural characters have been found. Three characters were best explained by a linear regression, indicating isometric growth. Eight characters were best explained by a quadratic curve, indicating gradual allometry. The remaining 12 characters were best explained by a split regression, indicating mainly isometric growth with abrupt allometry occurring at a specific SL (breakpoint). The first shift in morphometric values (a …