Several species of the planktonic free-living genus Oithona have been successfully used in the larviculture of marine fish and shrimp. However, few studies have been published that allow us to estimate the potential of Oithona nana culture under controlled conditions. This work evaluated the effect of the microalgae Isochrysis galbana and Chaetoceros calcitrans as single (200,000 cells/mL) and mixed diets (100,000 + 100,000 cells/mL) on population and individual growth, ingestion rate, number of spawnings, fertility, development time by stage, and sex ratio of O. nana. We cultured this copepod at 28 ± 0.5 °C, 35 PSU salinity, 125 lux, and 12:12 photoperiod. Results showed that diet had no effect on the final population level (6273–7966 ind/L) or on individual growth, nor on sex ratio, with less males than females. With C. calcitrans, O. nana had a higher filtration rate (57 ng C/ind/day). On the other hand, a mixed diet induced a higher number of spawns (0.4 events/day) and nauplii per spawn (23 ind). Similarly, a single or mixed diet, containing I. galbana, accelerated the development rate by 6.33–7.00 days. We concluded that O. nana can be cultured with both microalgae, indicating its potential use in an intensive system for production. However, more research is required to improve the productivity of O. nana rearing.

The transport of live fish for aquaculture is a key issue in the domestication of new species. National level programs were developed in Peru for controlled repopulation of Peruvian grunt (Anisotremus scapularis), reared in extensive systems or ongrown in floating cages, but these were limited by inadequate knowledge of the best transport parameters to ensure survival. This study aims to identify the effect of low-density (21.18 ± 4.38) medium (31.77 ± 6.57) and high-density in (42.36 ± 8.76 kg m⁻³), corresponding to 6 (48), 9 (72), and 12 (96 ind·bag⁻¹) ind·L⁻¹ during the transport time (8, 10, and 12 hr), on survival. Also seawater temperature, dissolved oxygen, pH, ammoniacal nitrogen (NH₃N), ammonia (NH₃), and ammonium (NH₄) were recorded at the end of transport. Survival at 8 and 10 hr at low-density was similar, but decreased at 12 hr. In contrast, all densities showed a greater effect after 12 hr of transport with 61.11 ± 17.35; 67.13 ± 7.13, and 70.49 ± 4.70% survival, respectively. Finally, the influence of the variables analyzed to contribute to survival and the sum of these, plus other parameters that were not measured, such as stress, leads to the conclusion of between 8 and 10 hr of transport time and not exceeding stocking density of 72 ind/bag (31.77 ± 6.57 kg m⁻³) should be used.

This study aimed to identify the effect of stocking density on growth, feed efficiency, and survival during the transition from Peruvian grunts (Anisotremus scapularis) fingerlings to juveniles. Fingerlings were reared in triplicate for 63 days until reaching the juvenile stage, at 1000 fingerling·m⁻³ (low-density LSD, 0.79 kg·m⁻³), 2000 fingerlings·m⁻³ (medium-density MSD, 1.58 kg·m⁻³), and 3000 fingerlings·m⁻³ (high-density HSD, 2.37 kg·m⁻³), and production performance parameters were evaluated. At the end of the experiment, results showed a negative correlation between stocking density and growth, individual growth, and the specific growth rate for HSD. The final biomass per treatment was 3.53 ± 0.26, 6.79 ± 0.08, and 7.70 ± 0.46 kg·m⁻³ for LSD, MSD, and HSD, respectively, the biomass harvest and weight gain were significantly lower for HSD. At the end of the experiment, there was no significant difference in survival (99%) among all treatments. Furthermore, the average food for each individual and the protein efficiency ratio were significantly lower for HSD, while the feeding efficiency was higher for HSD. In summary, our results indicated that initial biomass values above 1.42 kg·m⁻³ did not significantly improve growth and feed efficiency in the fingerlings rearing process.

Given the overexploitation of fisheries and the growing consumption of sea products, aquaculture is emerging as an alternative to meet the demand for protein at regional, national, and global levels. In northern Chile, the foothills of the Andes offer an opportunity for sustainable economic diversification. In this study, results of a rainbow trout (Oncorhynchus mykiss) culture in a recirculation system are presented, analyzing its growth and performance under altitude conditions. The research was carried out in Copaquilla, a small area in the foothills of northern Chile, 3000 m above sea level. Five thousand 15 g juvenile trout were acquired and transported by land from the Rio Blanco fish farm, successfully traveling more than 2100 km. During the 20-month-long culture, several growth parameters were evaluated, including specific growth rate, percentage of weight growth, feed conversion factor, survival, and Fulton’s condition factor. All these parameters were within the normal growth range for trout, evidencing good-quality growth of the organisms. The results offer evidence that rainbow trout farming at 3000 m above sea level is viable and presents a viable performance, opening new opportunities for aquaculture in northern Chile.

Anisotremus scapularis is a commercially important species in Peru, where its cultivation and management require technological strategies to minimize stress during aquaculture and fishing practices. Fish handling and transport can induce adverse physiological responses, making anesthetic use a key tool to mitigate these effects and enhance animal welfare. However, information on optimal doses, safety margins, and induction and recovery times of anesthetics in this species remains limited. This study evaluated the effects of eugenol and tricaine (MS-222) on the sedation of A. scapularis juveniles. A total of 450 individuals (9–10 cm total length) were exposed to different concentrations of eugenol and MS-222 (20, 40, 60, 80, and 100 mg/L) via immersion. Induction and recovery times were recorded, determining that the lowest concentrations allowing an optimal induction time (<6 min) and adequate recovery (<16 min) were 20–60 mg/L for eugenol and 80 mg/L for MS-222. These results provide essential information to optimize sedation protocols for A. scapularis juveniles, promoting more efficient handling with minimal impact on fish welfare in production and fishery management systems.

This study monitored the conditioning of rainbow trout (Oncorhynchus mykiss) broodstock in a closed culture system at 3000 m above sea level (m.a.s.l.) to evaluate the feasibility of this culture method and assess the first spawning of the species under these conditions as an alternative production route for the communities present in the foothills of Cordillera de los Andes, northern Chile. A total of 120 specimens with an initial weight of 170 g were used. They were maintained in a recirculation aquaculture system (RAS) composed of protected circular tanks, decanters, a biofilter, and oxygenation equipment. Fish growth was monitored through parameters such as specific growth rate (SGR), feed conversion ratio (FCR) and percent weight growth (PWG), parameters that were maintained within those reported by other authors for this species. The first successful spawning occurred after 12 months of broodstock conditioning, yielding 8570 eggs, of which 6569 hatched successfully. The success of this conditioning and spawning not only broadens the understanding of adaptability to high-altitude environments, but also provides evidence for the potential diversification of productive activities in foothill areas through aquaculture.