###### Abstract  
Aquaponics is the integration between aquaculture and hydroponics, where bacteria mediate the interaction between fish and plants, facilitating a mutually beneficial system. Although there have been numerous studies on aquaponics, there have been few studies focused on optimizing management parameters in small-scale systems for family farming. A key aspect is to find the appropriate culture density to maximize the production of both fish and plants. In aquaculture, introduced species have predominated due to their ease of management, great adaptability, and high growth rates; however, it is important to consider alternatives such as _Dormitator Iairfons_. To determine the effect of density on the yield of D. _Iairfons_ and chard _Beta vulgaris_ in an aquaponic culture, three culture densities of 10, 30, and 50 fish m\({}^{-3}\) were evaluated in triplicate with a fixed plant density of 20 plants m\({}^{-2}\). Nine experimental units (EU) were implemented consisting of 300 L Rotoplas(r) troughs, a settter (80 L), a biofiliter (80 L), and a submersible water pump connected to a nutrient film technique (NFT) system that represented the hydroponic component. The results obtained suggest that an intermediate stacking density (30 fish m\({}^{-3}\)) could provide a favorable balance between fish and plant performance and fish health. These findings contribute to the knowledge on the culture of this species in aquaponics.  
Beta vulgaris; backyard aquaponics; native fish; stress Received: 3 December 2024 7 December 2  
In aquaponics, nitrogenous wastes generated by fish and uneaten food are transformed by nitrifying bacteria into nitrates, which can be used by plants; the denitrified water can then be reintroduced to the fish [6; 7; 8]. This method is especially useful in urban areas, and in areas where the soil is poor and water is scarce, since it protects the water and does not impact the soil. Therefore, it is considered a suitable technology to achieve food security in a sustainable manner.  
Although there have been numerous studies on aquaponics, there have been few studies focused on optimizing management parameters in small-scale systems for family farming. A key aspect is to find the appropriate culture density to maximize the production of both fish and plants. Culture density refers to the number of fish that can be maintained in a given volume of water. An increase in culture density can lead to higher production, but it can also negatively affect the growth and health of the fish. Therefore, it is important to explore the effects of different culture densities in an aquaponic culture to optimize production in these sustainable systems.  
Introduced species (those relocated outside their natural range) have predominated in aquaculture because of their ease of management, great adaptability, and high growth rates. Unfortunately, the ecological consequences of their use have not been taken into account, e.g., [9; 10; 11; 12]; so, it is important to consider alternatives such as native species [13]. The Pacific fat sleeper _Dormitator latifrons_ is a fish native to tropical and subtropical climates, with a preference for waters with temperatures between 21 and 30 \({}^{\circ}\)C, with the ability to tolerate brackish water and low oxygen concentrations of down to 0.4 mg L\({}^{-1}\)[14; 15]. This species, which is native and commercially important in Central American countries, is widely distributed across most of the lagoons of the Mexican Pacific and is very abundant, representing one of the most characteristic species of the coastal lagoon system [16]. Therefore, in this study, the effect of different culture densities on the growth, survival, and blood parameters of _D. latifrons_ fish and the production of _Beta vulgaris_ chard in a small-scale aquaponic system was examined.