There is an increasing interest in the use of seawater in horticulture. The objective of this study was to evaluate Beta vulgaris var. cicla (Swiss chard) and its wild ancestor B. vulgaris spp. maritima (sea beet) as potential crop species for seawater hydroponics or aquaponics. Both species were grown in a floating system for leaf production with recurrent harvests. The nutrient solutions contained different concentrations of nitrate (1 and 10 mM) and a synthetic sea salt (0 and 10 g L⁻¹), in a factorial design, where the saline solution with a low nitrate level intended to mimic the typical nutritional conditions of saltwater aquaponics. In both species, increasing the salinity or reducing the N level in the nutrient solution reduced the crop yield and total dry biomass. In both Swiss chard and sea beet, the use of saline water resulted in a lower leaf concentration of K, Ca, Cu, and Mn, and a greater content of Na and Cl. In Swiss chard, an increase in Na and Cl and a decrease in K leaf content were found in successive harvests. On average, sea beet showed a higher leaf production and accumulation of nitrate than Swiss chard.

Saltwater aquaponics is a sustainable alternative system for food production. The success of this system largely depends on the selection of both fish and plant species, for which several features and criteria must be considered. This paper aims to identify the most suitable plant species for saltwater aquaponics by using a multi-criteria decision-making method also based on current literature. One simple model that contained one root criterion, four aggregated criteria, and four sub-criteria was created using DEXi software. The same model was evaluated considering two different salinity levels in the recirculating water: 10 (brackish water) and 35 (sea water) g L⁻¹. The relevance of the model structure was evaluated by the sensitivity analysis, through the ‘plus/minus-1′ analysis. Our results suggest that Salicornia europaea L. and Portulaca oleracea L. were suitable species for saltwater aquaponics at 35 g L⁻¹. Moreover, at 10 g L⁻¹, the suitable candidates were: Salicornia bigelovii Torr, S. europaea L., Beta vulgaris ssp. maritima (L.) Arcang, Atriplex hortensis L., and P. oleracea L. The DEXi analysis resulted in being an easy and effective tool to select proper species in similar contexts. DEXi can help to identify the hotspots of production processes, according to our results. Since the selected species are wild edible species or minor crops, the availability of their seeds is one of the main constraints of their cultivation in saltwater aquaponics.

This study assessed the effects of eco-efficient aquafeed formulations on the growth, body composition, nutrient retention, and flesh quality of rainbow trout (Oncorhynchus mykiss). Four extruded diets were tested: a conventional control (Ctrl) and three eco-efficient formulations (No-PAP, PAP, and Mix) combining single-cell ingredients, insect meal, selected plant proteins, and aquaculture by-products, with long-chain omega-3 fatty acids (DHA and EPA) supplied primarily from microalgae. Rather than isolating single-ingredient replacements, the objective was to evaluate the efficacy of complex, industry-feasible formulations designed for practical application. These experimental feeds were administered to 800 trout (initial body weight 63 g), distributed across four replicates per diet. After a 97-day trial, results showed no significant differences in growth performance (final weight, weight gain, and relative growth rate) between diets. Feed conversion ratios (~0.78) were within expected ranges for rainbow trout under these conditions. Fillet texture and composition were similar across all groups; however, trout fed the No-PAP diet developed a significantly more yellow tint in fillet color, likely attributed to xanthophyll pigments from plant- and algae-based ingredients. The environmental impact of the diets was driven by specific ingredient choices, as evidenced by a carbon footprint analysis ranging from 1.39 kg CO₂ eq. (PAP diet) to 2.36 kg CO₂ eq. (Ctrl diet). These findings demonstrate that the three alternative formulations matched the efficacy of conventional feed, offering a sustainable option for trout aquafeed production.

Captive breeding programs are essential for conserving the endangered salmonid Salmo carpio. However, standard hatchery operations rely on manual stripping, whose effects on Carpione reproductive physiology and welfare remain poorly understood. This preliminary study investigated the physiological and reproductive responses of captive female S. carpio to manual stripping. Forty-five mature females were assigned to three groups: pre-stripping (PRE), 1 day post-stripping (POST1), and 21 days post-stripping (POST21). Plasma concentrations of 17β-estradiol, testosterone, progesterone, cortisol, glucose, and antioxidant enzyme activities (SOD, CAT, GPx) were assessed alongside ovarian histology. While no effects were detected on circulating steroid or glucose levels, POST21 females showed significantly higher cortisol and increased SOD and CAT activities than PRE and POST1 fish (p < 0.05), while both POST1 and POST21 showed higher GPx activity compared to PRE, indicating a delayed modulation of stress response and oxidative challenge after the stripping event. Ovarian histology revealed no evident histopathological alterations. PRE group ovaries were characterized by the presence of primary growth and tertiary vitellogenic oocytes. Primary growth oocytes were identified in all the experimental groups. Secondary vitellogenic oocytes, together with post-ovulatory follicles and atretic oocytes, were observed at POST1. At POST21, histological examination revealed primary growth and early vitellogenic oocytes, while mature oocytes were also identified macroscopically, supporting the persistence of ovarian reproductive activity during the reproductive season. Overall, females maintained ovarian activity throughout the examined period, while delayed systemic stress during post-spawning recovery was observed in the POST21 group. Broodstock management should therefore include adequate recovery periods and reduce handling to support welfare and reproductive performance.