Comparative growth studies on Lethrinus lentjan, Lacépède 1802 and Lethrinus mahsena, Forsskål 1775 (Pisces, Lethrinidae) in the Red Sea

Growth characteristics for two lethrinids, Lethrinus lentjan Lacépède 1802 and Lethrinus mahsena, Forsskål 1775 in the Red Sea off Jeddah were studied. With ages determined by scale readings, back-calculated lengths up to the seventh year of life were obtained for each species. Regressions of fish length on scale radius were also computed. Growth in weight was highest during the third and fourth years of life for L. lentjan and L. mahsena, respectively. Within each species, males and females gave virtually identical growth rates. Three exponential equations were derived for each species, representing the weight/length relationship separately for males, females and the sexes combined. Condition factor ( K) values were also determined and variations of these values with fish size and month of capture were studied. The parameters of von Bertalanffy's growth equation were estimated for the two studies. Sex ratio at age suggests sex reversal from female to male during the fifth and seventh year of life for L. lentjan and L. mahsena, respectively.