Microscopic marine bacteria interacting with fish larvae

Unlock the Secrets of Fish Farming: How Probiotics Can Save Your Larvae

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Kai Mendoza in Science & Nature August 2025 • 4 min read.

"Discover how Pseudoalteromonas sp. can boost survival rates in Seriola lalandi larval cultures."


Aquaculture, or fish farming, is a rapidly growing industry essential for meeting the global demand for seafood. One of the most significant challenges in aquaculture is ensuring high survival rates during the larval stages. The golden fish, Seriola lalandi, is a highly sought-after species in both national and international markets. However, its larval survival rates in culture remain low, primarily due to poor larval quality.

Traditional methods often fall short in providing the necessary support for these fragile creatures. Factors such as inadequate nutrition, disease outbreaks, and suboptimal environmental conditions contribute to high mortality rates. This is where probiotics come into play. Probiotics, beneficial bacteria that improve the host's health, have shown promise in enhancing larval survival and overall aquaculture productivity.

A groundbreaking study has explored the potential of Pseudoalteromonas sp., a marine bacterium, as a probiotic for Seriola lalandi larval cultures. This research delves into the isolation, identification, and evaluation of Pseudoalteromonas sp. to determine its probiotic capabilities, offering a potential solution to improve larval survival rates and revolutionize fish farming practices. For fish farmers and aquaculture enthusiasts, understanding this research could unlock new strategies for success.

The Promise of Probiotics in Aquaculture

Microscopic marine bacteria interacting with fish larvae

Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. In aquaculture, probiotics can improve the gut microbiota, enhance immune responses, and increase resistance to diseases. The use of probiotics in larval cultures has shown remarkable improvements in survival rates, making it a promising alternative to traditional methods. The key is to identify and utilize the right probiotic strains for specific fish species.

The study focused on isolating bacteria from the microbiota of Seriola lalandi to identify potential probiotic candidates. Researchers isolated 46 strains of bacteria from both juvenile and larval S. lalandi. These strains were then subjected to rigorous testing, including phylogenetic analysis, antibacterial assays, and assessments of hemolytic, lipolytic, and proteolytic activities.

The research methodology included several key steps:
  • Isolation and Identification: Bacteria were isolated from S. lalandi juveniles and larvae and identified at the molecular level using 16S rRNA gene analysis.
  • Phylogenetic Analysis: Evolutionary relationships among the isolated bacteria were determined.
  • Antibacterial Assays: The ability of the bacteria to inhibit pathogenic bacteria was tested.
  • Enzymatic Activity Tests: Hemolytic, lipolytic, and proteolytic activities were assessed to determine potential harmful effects.
The results were compelling. Out of the 46 isolated bacteria, 42% belonged to the genus Pseudoalteromonas. Nine of these Pseudoalteromonas strains exhibited inhibitory activity against pathogenic bacteria. Notably, one strain was negative for hemolysis, proteolysis, and lipolysis, indicating its safety and potential as a probiotic. This particular strain of Pseudoalteromonas sp. emerged as a promising candidate for improving larval survival in Seriola lalandi cultures.

A New Era for Sustainable Aquaculture

The findings of this study suggest that incorporating Pseudoalteromonas sp. as a probiotic in Seriola lalandi larval cultures could significantly enhance survival rates. The researchers propose mixing this beneficial bacterium with microalgae, commonly used to feed rotifers and artemia, which serve as vectors for delivering the probiotic to the larvae. This approach aligns with the growing trend of sustainable aquaculture practices, reducing reliance on antibiotics and promoting healthier, more resilient fish populations. By understanding and applying these findings, fish farmers can look forward to a future of more productive and sustainable aquaculture.

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Everything You Need To Know

1

How do probiotics like *Pseudoalteromonas* sp. specifically improve the survival rates of *Seriola lalandi* larvae in fish farming?

Probiotics, particularly *Pseudoalteromonas* sp., enhance the health and survival rates of *Seriola lalandi* larvae by improving their gut microbiota, boosting immune responses, and increasing resistance to diseases. The introduction of beneficial bacteria helps to create a more balanced and supportive environment for the larvae, leading to improved overall aquaculture productivity.

2

What specific methodologies were employed to isolate and identify probiotic candidates from *Seriola lalandi* in the study?

Researchers isolated 46 bacterial strains from *Seriola lalandi* juveniles and larvae, focusing on identifying potential probiotic candidates. They conducted phylogenetic analysis to understand evolutionary relationships, antibacterial assays to test inhibition of pathogens, and enzymatic activity tests (hemolytic, lipolytic, proteolytic) to assess potential harm. The isolation and identification relied on 16S rRNA gene analysis at the molecular level.

3

What were the key findings regarding the effectiveness of *Pseudoalteromonas* strains as probiotics for *Seriola lalandi* larval cultures?

The study identified that 42% of the isolated bacteria belonged to the genus *Pseudoalteromonas*. Nine *Pseudoalteromonas* strains showed inhibitory activity against pathogenic bacteria. One strain was negative for hemolysis, proteolysis, and lipolysis, indicating its safety and potential as a probiotic for *Seriola lalandi* larval cultures.

4

How is *Pseudoalteromonas* sp. proposed to be administered to *Seriola lalandi* larvae in aquaculture settings, and why is this method beneficial?

The researchers suggest mixing *Pseudoalteromonas* sp. with microalgae, a common feed for rotifers and artemia, which then serve as vectors to deliver the probiotic to the larvae. This method ensures the *Seriola lalandi* larvae effectively receive the probiotic, promoting better health and survival rates during their crucial early development stages. This approach aligns with sustainable aquaculture practices.

5

What are the limitations of traditional methods in ensuring high survival rates of *Seriola lalandi* larvae, and how does using *Pseudoalteromonas* sp. address these limitations?

Traditional methods often fall short due to issues like inadequate nutrition, disease outbreaks, and suboptimal environmental conditions, leading to high mortality rates in *Seriola lalandi* larval cultures. Probiotics, such as *Pseudoalteromonas* sp., address these issues by improving the larval gut microbiota, enhancing immune responses, and increasing disease resistance, offering a more effective and sustainable solution to increase larval survival rates.

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