Effect of salinity on the body shape of sword tail, Xiphophurus helleri, during early developmental stage

Abstract

This study aimed to investigate the effect of an isosmotic point of salinity i.e. 12 ppt on the body shape of sword tail, Xiphophurus helleri, during the early development using geometric morphometric approach. In total sixty newly hatched larvae reared in two salinity treatments (0.5 and 12 ppt) for a period of two months. Then the left side of the specimens were photographed and sixteen landmark-points defined and digitized on 2D picture using tpsDig2 software to extract body shape data. The extracted data after GPA analysis, were analyzed using DFA/T-test Hoteling. The results revealed significant different between body shape of two treatments showing shorter snout, head and caudal peduncle, lower head and body depth, anterior position of gill and longer dorsal fin in the group exposed to higher salinity. The results confirmed that salinity as important environmental parameter impacts and regulate the body shape of swordtail during early ontogenic development.