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.