Document Type : Original Article
Authors
1
Department of Fisheries, Faculty of Natural Resources and Environment, Behbahan Khatam Alanbia University of Technology, Behbahan, Iran.
2
Department of Fisheries, Natural Resources faculty, University of Tehran, Karaj, Iran.
3
Native Fishes Reproduction Center of Sousangerd, Khouzestan Fisheries Organization, Sousangerd, Iran.
Abstract
During the early development stages, fish larvae undergo complex changes that result in improved their adaptation to their environment. Shirbot, Arabibarbus grypus, is one of the economical valuable fish in the southwest of Iran due to its high-quality meat and marketing. Hence, the current study was conducted to investigate the morphological changes in its larvae during early development stages up to 50 days post-hatching. The larvae were obtained from the native fish breeding center of Khuzestan Province. Larvae were sampled daily for the first two weeks and then every 5 days until 50 dph. To study the body shape changes of larvae, geometric morphometric technique with the definition of 9 landmark-points was used. Relative warp and regression analysis based on P-value obtained from 1000 replications were used to study the morphological changes during early developmental stages. The changes of morphological stages were visualized based on the deformation grids compared to the consensus one. Based on the results of the geometric morphometric analysis, the larval stages of this species from hatching up to 50 days can be divided into four distinct stages of (1) 1-4, (2) 5-25, (3) 30-35 and (4) 40-50 DPH in terms of morphological changes. The inflexion point of morphological changes was 20 dph. The end of stage 1 coincided with the beginning of exogenous feeding, and stage 2 was more concerned with changes in the body shape, including the increase of the body depth as well as increasing pigment density, especially in the dorsal part of the body, indicating increased fish adaptability for greater maneuverability, camouflage, and increased the ability to prey small organisms. In the third and fourth stages, this species is almost in the form of a miniature form of adult fish, one but with a relatively elongated, fusiform body shape.
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