The Jewel Cichlid (Hemichromis bimaculatus) is a freshwater ornamental fish that holds significant importance in the aquaculture industry due to its unique morphological characteristics. The growth and development of the skeletal system in this fish are considered key factors in its breeding quality and overall health. Since water temperature is one of the most critical environmental factors influencing fish growth and development, this study aimed to investigate the effect of water temperature on the ossification process of the Jewel Cichlid. To this end, a 60-day experiment was conducted under controlled laboratory conditions at three temperature treatments: 26°C, 29°C, and 32°C. At the end of the experimental period, fish samples were cleared using a sodium borate solution, and double staining with Alcian blue (for cartilage) and Alizarin red (for bone) was performed to examine the skeletal structure. Additionally, allometric analyses were conducted to eva‎luate changes in relative skeletal growth. The results indicated that increasing temperature had a significant effect on accelerating the ossification process. In the 32°C treatment, the skull and associated structures ossified faster than other body regions, and the fish exhibited ossification features in a shorter time. In contrast, in the 26°C treatment, the ossification process occurred at a slower rate, and some skeletal elements remained incompletely developed by the end of the experiment. Furthermore, allometric analyses revealed that the growth of certain skeletal regions was disproportionate compared to others, showing different patterns at varying temperatures. Specifically, at higher temperatures, the growth of the skull, dorsal fin, and caudal fin regions was faster than other body parts, while the vertebral column and pelvic girdle exhibited more uniform growth. Increased temperature also led to changes in skeletal proportions, optimizing body ratios at higher temperatures and accelerating the growth of key regions involved in movement and balance. These changes could influence the fish's locomotor performance, biological efficiency, and environmental adaptability. As a result, valuable insights were gained regarding the impact of water temperature on the skeletal development of the Jewel Cichlid, which can be utilized to optimize breeding conditions, improve growth quality, and enhance productivity in the breeding and cultivation of this ornamental fish. Additionally, the study of allometric patterns at different temperatures provides a better understanding of fish growth and their adaptation to varying environmental conditions, which can be applied in evolutionary studies and growth biology of fish.

يزدان كيواني , فاطمه پيكان حيرتي

سالار درافشان , اميرحسين جلالي حاجي آبادي