The integration of marine shrimp and tilapia farming appears to be a viable alternative in a biofloc system; however, there is no consensus on the spatial arrangements of the cultured animals.
The biofloc technology is characterized as a super-intensive production system for aquatic organisms, with or without water exchange, and the recycling of nutrients within the same tank through the stimulation of microbiota that forms microbial aggregates.
However, there are no studies that identify the optimal spatial arrangement for integrating tilapia into the biofloc system for marine shrimp cultivation, which could combine the biological and economic advantages of this integration.
In this regard, researchers from the Institute of Oceanography at the Federal University of Rio Grande and the School of Marine Sciences at Pontifical Catholic University of Valparaíso compared the performance of marine shrimp (Litopenaeus vannamei) and tilapia (Oreochromis niloticus) at high densities in polyculture and multitrophic systems, and their effects on water quality, especially organic matter (biofloc).
Biofloc limitations
Despite the various advantages of the biofloc system, one of its main limitations is the accumulation of suspended solids, which can negatively affect the cultured organisms.
Aquaculturists use various strategies to maintain suspended solids concentrations within the target species’ range. These strategies include the use of mechanical clarifiers. This equipment is easy to operate but requires extra space and is directly dependent on the type of biofloc.
Another strategy to remove excess suspended solids is through integration with other species of interest in aquaculture that can consume these particles.
Integrated Multitrophic Aquaculture (IMTA)
Integrated Multitrophic Aquaculture (IMTA) has gained importance in recent decades due to the need to promote environmentally friendly technologies while maintaining the productivity of aquaculture systems.
IMTA is based on the concept that waste, such as unconsumed feed, feces, and metabolic excretions from one species, can be used to feed species from different trophic levels within the same cultivation system.
Thus, using the IMTA approach in biofloc systems can be a way to address the accumulation of total suspended solids.
Experimental Design
The researchers implemented an experiment consisting of three treatments:
- MONO – Monoculture of shrimp;
- IMTA ST – Integrated cultivation of tilapia and shrimp in the same tank; and,
- IMTA DT – Integrated cultivation of tilapia and shrimp in separate tanks.
They also used a density of 204 shrimp m-3 and 100 fish m-3. At the beginning of the experiment, the shrimp and fish had initial weights of 2.67 g and 7.44 g, respectively.
Effects on Water Quality
Several studies have reported that integrating tilapia with marine shrimp in the same or separate tanks does not affect water quality parameters for either of the cultured species. In the study, the values of total suspended solids and turbidity remained at acceptable levels for both species.
“Despite the decrease in the average value of total suspended solids, the presence of tilapia does not affect the microbial community in the biofloc system due to the lack of significant differences in the average value of nitrogen compounds in the presence of the fish,” the researchers report.
Performance of Shrimp and Tilapia
“The presence of tilapia in the integrated system with shrimp in the same tank negatively affected the performance of shrimp rearing,” they emphasized.
They also reported that the combined shrimp and fish density represents an initial total biomass 2.2 times greater than that of shrimp cultivated in the MONO and IMTA DT treatments, contributing to the poorer zootechnical performance of shrimp in the IMTA ST system.
In the IMTA ST treatment, a half of the feed conversion factor was recorded, with double the growth and productivity of tilapia when compared to the IMTA DT system.
Finally, the researchers report that: “The final biomass of the IMTA DT and IMTA ST treatments doubles the final biomass of the shrimp monoculture, justifying the use of IMTA and demonstrating that it is an ecologically and economically viable alternative. It is worth noting that it was possible to increase the total biomass produced in the IMTA DT treatment by 175% without compromising the specific growth rate and feed conversion of shrimp.”
Conclusion
The main conclusions of the study are:
- Tilapia proved to be efficient in consuming and maintaining levels of total suspended solids in the integrated system with shrimp, without affecting water quality.
- The zootechnical performance of L. vannamei shrimp was negatively impacted when grown in the same tank as tilapia.
- In this regard, the researchers conclude that the best-integrated super-intensive system for L. vannamei and O. niloticus at a tilapia-shrimp ratio of 0.49 is in separate tanks, as observed in the IMTA DT treatment.
“Under the tested experimental conditions, it is recommended that shrimp and fish be cultured in separate tanks so that the producer can have two end products to market at the end of the production cycle without negatively affecting shrimp production,” they concluded.
The study was funded by the ASTRAL Project—H2020.
Reference (open access)
Holanda, M.; Wasielesky, W., Jr.; de Lara, G.R.; Poersch, L.H. Production of Marine Shrimp Integrated with Tilapia at High Densities and in a Biofloc System: Choosing the Best Spatial Configuration. Fishes 2022, 7, 283. https://doi.org/10.3390/fishes7050283
