Effects of seaweed-mediated copper nanoparticles on antibacterial activity and survival rate of Guppy ornamental fish

Abstract Objective The purpose of this study was to develop ecofriendly and sustainable copper nanoparticles (CuNPs) using Padina pavonica extract. The CuNPs were characterized using scanning electron microscopy (SEM) for morphological analysis, energy dispersive X-ray (EDS) spectroscopy for elemental composition, Fourier transform infrared (FTIR) spectroscopy for functional group identification, and UV-visible spectroscopy for optical properties. We evaluated the toxicity and survival rates of Guppy Poecilia reticulata larvae that were subjected to varied CuNP concentrations to determine the best concentration range for future aquaculture uses. Methods The different characterization and stability of the synthesized CuNPs were investigated using SEM, EDS, FTIR, and UV-visible spectroscopy. To evaluate safe aquaculture exposure levels, the Guppy larvae were exposed to varied CuNP concentrations and survival rates were monitored over a 72-hour period. Results The biosynthesized CuNPs exhibited characteristic surface plasmon resonance peaks at 260 nm, confirming their formation, with FTIR revealing the involvement of functional groups like O-H and O-SO3H in nanoparticle capping. The SEM analysis showed irregular, aggregated CuNPs, with sizes ranging from 50 to 200 nm. Energy dispersive X-ray spectroscopy confirmed the elemental composition, including copper, oxygen, chlorine, and carbon. Conclusions This article describes a sustainable and environmentally acceptable method for manufacturing CuNPs with Padina pavonica extract as a natural reducing agent. We established an appropriate concentration range by comparing the toxicity and survival rates of Guppy larvae that were exposed to different CuNP concentrations. The findings provide important insights into the safe use of copper nanoparticles in aquaculture, which benefits both aquatic organism health and environmental sustainability.