The tambaqui (Colossoma macropomum) is gaining ground in Amazonian and African aquaculture due to its rapid growth and adaptability. This study explores how natural food sources in ponds can complement commercially produced feed, potentially reducing operating costs and environmental impact.
A team of scientists from EMBRAPA and São Paulo State University investigated how natural food intake affects tambaqui growth in both fertilized and unfertilized ponds. The scientists used sophisticated techniques such as stable isotope analysis and stomach content examination to understand what the fish were consuming. They also assessed the impact of fertilization on the availability of natural food, fish performance, and production costs.
Exploring Natural Food Sources for Tambaqui Growth
Traditionally, aquaculture relies heavily on formulated feeds. However, natural food sources available within ponds can play a significant role.
To address nutrient limitations and stimulate natural food production within ponds, fish farmers employ organic and inorganic fertilization techniques. This is particularly beneficial during the early growth stages of fish, when fry (young fish) may struggle to fully utilize commercially produced feed. Studies have demonstrated that fertilization can significantly enhance fish productivity in various species, with increased levels of phytoplankton (microscopic algae), zooplankton (tiny animals), and other food sources.
The Power of Balance: Combining Natural and Manufactured Feeds
While fertilization can boost natural food production, it is not a standalone solution. Most studies have not considered the impact of fertilization alongside the use of formulated feeds. Relying solely on enhanced natural food sources limits overall productivity, especially when population densities (number of fish per unit area) are high. The most successful aquaculture systems combine fertilization with an “allogenic diet,” an external source of nutrients, typically in the form of commercially produced fish feed. This approach optimizes pond productivity.
While allochthonous feeds are essential in intensive aquaculture, natural food sources play a crucial role. They can effectively complement or even partially substitute formulated feeds in certain situations. This is particularly important for species that lack adequate and well-balanced commercial diets. Understanding how fertilization interacts with allochthonous feeding strategies is key to improving aquaculture efficiency and aligning with restorative practices.
The Experiment: Fertilized versus Unfertilized Ponds
Juvenile tambaqui were placed in fertilized (Fert) and unfertilized (NoFert) ponds for 10 months. Fert ponds received regular nitrogen and phosphorus fertilization to promote the growth of natural food sources. Researchers monitored various aspects, including:
- Food conversion ratio: This metric measures how efficiently the fish convert food into body weight. Lower ratios indicate better conversion.
- Stomach contents: Stomach content analysis revealed the types of natural food the fish consumed.
- Fish growth and survival: Scientists tracked the weight gain and overall survival rate of the tambaqui.
- Water quality: Water parameters were monitored to assess the impact of fertilization.
The Power of Plankton: Natural Foods Boost Efficiency
The study yielded some fascinating results. Fish in fertilized ponds exhibited a lower food conversion ratio, indicating they were more efficient in converting natural and formulated feed into growth. Stomach content analysis revealed that tambaqui consumed a variety of natural food sources, including insects, vegetation, and small crustaceans called cladocerans.
Curiously, plankton (tiny organisms that thrive in water) significantly contributed to tambaqui muscle formation, especially in fertilized ponds (39.4% compared to 10.7% in unfertilized ponds).
The Fertilization Advantage: Boosting Natural Food Webs
The study compared tambaqui growth, survival, and overall production in fertilized and unfertilized ponds. While fertilization did not significantly impact fish growth or survival directly, it did generate a crucial benefit: increased zooplankton density. By promoting phytoplankton (microscopic plant life) growth, fertilization created a more abundant natural food web for tambaqui to consume. This translates into potentially lower reliance on commercially produced fish feed, reducing costs and environmental impact.
Conclusion: Tambaqui’s Adaptability Paves the Way
The study highlights the remarkable adaptability of tambaqui. This fish can effectively utilize both natural food sources and commercially produced feeds without compromising its growth.
By incorporating natural food sources into tambaqui aquaculture, producers can potentially enhance fish health, reduce environmental impact, and optimize production costs.
The study is part of the BRS Aqua Program, funded by the Brazilian Development Bank—Technologic Fund (BNDES-Funtec), Ministry of Agriculture, Livestock And Food Supply (MAPA), Brazilian National Council for Scientific and Technological Development (CNPq), and the State Foundation for Research and Development of Mato Grosso do Sul (FUNDECMS).
Reference (open access)
Lima, A. F., Dos Reis, A. G., Costa, V. E., & Valenti, W. C. (2024). Natural Food Intake and Its Contribution to Tambaqui Growth in Fertilized and Unfertilized Ponds. Fishes, 9(4), 139. https://doi.org/10.3390/fishes9040139
