High-density farming practices can induce stress in fish, compromising their health and growth. To mitigate these effects, supplements are often used to promote fish health and well-being. Calcium disodium EDTA (CaNa2EDTA), or EDTA, is a chelating agent that has demonstrated antioxidant and immunomodulatory properties.
Researchers from Lahore College for Women University, Purdue University, and Suez University studied the effects of EDTA supplementation on the growth, immune response, and antioxidant activity of Nile tilapia (Oreochromis niloticus) reared under different stocking densities.
The Challenge of High-Density Aquaculture
While high-density aquaculture increases production efficiency, it presents several critical challenges. Overcrowding can lead to:
- Increased stress: Competition for resources, limited space, and deteriorating water quality can induce significant stress in fish. This stress manifests in elevated cortisol levels, suppressed immune function, and greater susceptibility to diseases.
- Reduced growth: Stress can negatively impact growth by inhibiting growth hormone release and altering the expression of growth-related genes, such as somatostatin-1 (SST-1).
- Oxidative stress: Overcrowding can trigger oxidative stress, leading to the production of reactive oxygen species (ROS) and causing cellular damage. Poor water quality and heavy metal presence can exacerbate this oxidative stress.
EDTA: A Potential Solution
EDTA is a chelating agent that binds to metal ions, reducing their bioavailability and mitigating their potential harm to fish health. By incorporating EDTA into fish feed, this study aimed to:
- Reduce oxidative stress: By chelating heavy metals and preventing them from catalyzing free radical reactions, EDTA can help mitigate oxidative stress and protect fish cells from damage.
- Improve water quality: By binding heavy metals, EDTA can contribute to improved water quality, reducing the negative impacts of metal contamination on fish health.
- Enhance growth performance: By reducing stress and improving overall health, EDTA supplementation may potentially enhance growth rates and feed efficiency in tilapia.
Methods
In this study, researchers reared Nile tilapia under three different stocking densities: low (2.00 kg/m³), medium (3.50 kg/m³), and high (5.00 kg/m³). Each density group was fed one of four EDTA supplementation levels: 0 g/kg (E0), 5 g/kg (E1), 10 g/kg (E2), and 15 g/kg (E3) for 60 days. Each diet was tested in triplicate, with 66 fish per replicate in the low-density group, 116 fish per replicate in the medium-density group, and 166 fish per replicate in the high-density group.
Results
The results showed that the low-density group exhibited better growth than the medium- and high-density groups. Among all groups, those fed the E1 diet demonstrated superior growth compared to other diets.
The study found significant changes in the chemical composition of fish and digestive enzyme activity across all treatments. Antioxidant enzyme and cortisol levels were higher in the high-density group compared to the low- and medium-density groups. However, fish in the high-density group fed the E1 diet exhibited the lowest levels of antioxidant enzymes and cortisol.
Malondialdehyde levels were higher in the high-density group than in the low- and medium-density groups, with the lowest levels observed in fish fed the E1 diet within the high-density group.
Implications for Aquaculture
This study provides valuable insights into the potential benefits of EDTA supplementation for mitigating the harmful effects of high-density tilapia farming. The findings suggest that:
- EDTA supplementation, particularly at a dose of 5 g/kg, can significantly improve growth performance in tilapia under high-density conditions.
- EDTA supplementation can effectively alleviate stress responses in fish by reducing cortisol levels and modulating antioxidant enzyme activity.
These findings have important implications for sustainable aquaculture practices, demonstrating a promising strategy to enhance fish health and well-being while maximizing production in intensive farming systems.
Conclusion
This study highlights the potential benefits of EDTA supplementation in intensive tilapia farming. The results suggest that EDTA supplementation can improve growth and antioxidant responses in tilapia, particularly at a dose of 5 g/kg under high-density conditions. This approach could be beneficial for reducing stress and enhancing the overall health and well-being of tilapia in intensive farming systems.
Contact
Shafaq Fatima
Department of Zoology, Faculty of Natural Sciences, Lahore College for Women University
Lahore, Punjab, Pakistan
Email: shaff01@pfw.edu
Reference (open access)
Komal W, Fatima S, Minahal Q, Liaqat R, Abdul Latif A, Hussain AS (2025) Impact of CaNa2EDTA fortification on growth, antioxidant activity and stress-related gene expression in tilapia (Oreochromis niloticus) at different stocking densities paradigms. PLoS ONE 20(1): e0316629. https://doi.org/10.1371/journal.pone.0316629
