Lactobacillus Enhances Tilapia Resistance to Streptococcosis

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By Milthon Lujan

In the tilapia aquaculture industry, the pursuit of increased growth rates and disease resistance in cultured fish has become a top priority. Dietary supplementation has emerged as a promising strategy to enhance the health and productivity of aquatic species.

Researchers from the IPB University’s Department of Aquaculture and the House Wellness Foods Corporation recently conducted a study examining the supplementation of tilapia feed with heat-killed Lactobacillus plantarum and its impact on resistance to Streptococcus agalactiae.

During a 90-day feeding trial, the researchers explored the effects of different levels of heat-killed L. plantarum L-137 supplementation, ranging from 10 mg/kg to 250 mg/kg, on tilapia growth and resistance to S. agalactiae infections.


Streptococcosis, caused by the bacterium Streptococcus agalactiae, is a disease that leads to significant losses in the tilapia industry. Infections caused by S. agalactiae result in highly cumulative mortality rates in tilapia farms, leading to substantial economic losses.

In intensive tilapia farming, streptococcosis has become a prevalent disease, particularly in conditions with low dissolved oxygen levels and high ammonia levels.

Experimental Design

To conduct the study effectively, the researchers formulated various dietary treatments, each containing different levels of heat-killed L. plantarum L-137:

  • Control Treatment: A diet without heat-killed L. plantarum.
  • LP20 (10 mg/kg): A diet containing 10 mg/kg of heat-killed L. plantarum L-137 preparation (LP20, which contains 20% heat-killed L. plantarum L-137).
  • LP20 (20 mg/kg): A diet containing 20 mg/kg of LP20.
  • LP20 (100 mg/kg): A diet containing 100 mg/kg of LP20.
  • LP20 (250 mg/kg): A diet containing 250 mg/kg of LP20.
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All diets were carefully formulated to maintain equal levels of protein and energy.

Improvement in Growth

According to the study’s results, supplementation with heat-killed L. plantarum L-137 had a positive impact on tilapia growth performance. This finding is of paramount importance to aquaculturists seeking to optimize yield and production efficiency.

“The improved growth performance in the L. plantarum-supplemented treatments and similar feed conversion ratios among all treatments could be related to a significant difference in food consumption,” the researchers reported. They also suggested that the supplementation of ingredients might affect diet palatability, thereby improving food intake, especially considering that the diet in this trial used low-fishmeal and high-plant-based ingredients.

Resistance to S. agalactiae

One of the most noteworthy outcomes of this research is the potential of heat-killed L. plantarum L-137 to strengthen tilapia resistance against Streptococcus agalactiae infections.

“Our research demonstrated that after being challenged with S. agalactiae, the leucocytes in the 100 and 250 mg/kg LP20 treatments were significantly higher than in the control,” the researchers highlighted.

Based on the study’s results, the higher level of leucocytes, combined with increased survival after S. agalactiae challenge, demonstrates LP20’s ability to enhance immune function when supplemented at higher doses.

Given the economic losses often associated with disease outbreaks in aquaculture, this finding underscores the importance of dietary supplementation in disease management.


In the ever-evolving field of aquaculture, optimizing fish growth and health remains a top priority. Research on the supplementation of tilapia diets with heat-killed L. plantarum L-137 offers a promising avenue for achieving these objectives.

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With the potential to improve growth performance and enhance resistance to pathogenic challenges, this dietary approach holds great promise for the future of sustainable and productive tilapia farming. As the aquaculture industry continues to seek innovative solutions, heat-killed L. plantarum L-137 emerges as a valuable tool in the pursuit of healthier and more profitable fish farming practices.

Based on the study’s findings, scientists recommend:

  • For enhanced growth, a dietary supplementation level of 10 to 20 mg/kg of LP20 is recommended. This dosage range appears to strike a balance between improved growth and cost-effectiveness.
  • For higher protection against S. agalactiae infection, a more robust dietary supplementation level of 250 mg/kg of LP20 feed is recommended. This higher dosage may be particularly valuable in situations where disease risk is elevated.

Reference (Open Access):
Julie Ekasari, Vini Nur Mirza, Ichsan Achmad Fauzi, Kyohei Hashimoto, Muhammad Agus Suprayudi, “Evaluation of Growth and Health Performance of Juvenile Tilapia Oreochromis sp. Fed with Various Supplementation of Heat-Killed Lactobacillus plantarum,” Aquaculture Nutrition, vol. 2023, Article ID 8860364, 8 pages, 2023. https://doi.org/10.1155/2023/8860364

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