Morphological and chemical properties of calcined fish bones (Carassius Gibelio and Esox lucius) for biomaterial applications

Carassius gibelio (Cg), an omnivorous invasive species in European and Turkish waters, originated in Asia and spread to Europe in the 17th century. In contrast, the carnivorous Esox lucius (El) (northern pike) inhabits rivers, lakes, and brackish waters across the Northern Hemisphere. Utilizing these species as biomaterials can supports waste management and biocompatible material synthesis. In this study, the morphological and chemical characteristics of calcined fish bone powders from different anatomical parts, including head bone (HEB), otolith bone (OTB), operculum bone (OPB), and spine bone (SPB), were systematically investigated. The particle size distribution analysis revealed that Cg-HEB exhibited the smallest particle size (53.91 μm), whereas El-OTB had the largest (431.54 μm). Morphological analysis confirmed a predominant rod-shaped structure for both Cg and El samples, except for El-OTB, which exhibited a distinct morphology. X-ray diffraction (XRD) analysis confirmed hydroxyapatite (HA) as the primary crystalline phase in all samples, accompanied by the presence of β-tricalcium phosphate (β-TCP). Fourier transform infrared (FTIR) spectroscopy further validated the presence of phosphate (PO₄³⁻) bands at 1030–1100 cm⁻¹ and 560–600 cm⁻¹, reinforcing HA as the dominant phase. The Ca/P ratio analysis indicated that Cg-SPB had a slightly lower ratio (0.07 less) than the stoichiometric Ca/P ratio of human bone, suggesting an increased β-TCP content. Conversely, El samples generally exhibited lower Ca/P ratios compared to Cg samples. These findings emphasis the potential of fish bone-derived materials for biomedical, particularly in bone tissue engineering.