Evaluation of Physicochemical Parameters and Microbiological Dynamics in the Microenvironment of Carassius auratus in an Aquaponic System
Andrea Moreno Huerta, Laura Hernández-Rizo, Rosa Angélica Rangel-PorrasIntroduction:
Aquaponic systems integrate microbial and plant-mediated processes to transform fish-derived waste into bioavailable nutrients. The aim of this study was to assess physicochemical parameters within the Carassius auratus microenvironment in a small-scale aquaponic system and their implications for plant development.
Methods:
An aquaponic system with two Carassius auratus and a tezontle grow bed operated for 21 weeks. Physicochemical parameters were monitored in both compartments. Growth and survival of evaluated crops were recorded, and microbial characterization included Gram staining, catalase, oxidase, and presumptive coliform detection.
Results:
In the small-scale system, lettuce and coriander achieved a 100% survival rate, with mean total growth of 31.5 cm and 33.8 cm, respectively. Radish and tomato, by contrast, exhibited markedly lower survival rates of 40% and 75%, with mean total growth of 21.52 cm and 54.2 cm; neither species produced fruit. Total ammonium nitrogen in the aquarium correlated positively with nitrates, phosphates, and hardness in the grow bed. Elevated alkalinity negatively affected plant performance. Gram-positive bacteria predominated in the aquarium, and Gram-negative bacteria in the grow bed.
Discussion:
Results indicated progressive system maturation, with alkalinity acting as a buffer and nitrification occurring mainly in the grow bed. Lower pH increased phosphate availability, and decreasing hardness suggested plant uptake of calcium and magnesium. Leafy crops benefited from nitrate-driven growth, while fruiting species likely faced nutrient limitations.
Conclusions:
Waste generated within the Carassius auratus microenvironment sustained nutrient cycling and vegetative plant growth in small-scale aquaponic systems, highlighting chemicalbiological interactions underlying system stability and productivity.