DO-increasing effects of a microscopic bubble generating system in a fish farm.

Area of Science:

• Aquaculture Engineering
• Marine Biology
• Environmental Science

Background:

• Marine fish farming faces challenges with maintaining optimal water quality, particularly dissolved oxygen levels.
• Fluctuations in dissolved oxygen can negatively impact fish health, growth, and survival rates in aquaculture systems.
• Existing methods for oxygenation may be costly or inefficient in large-scale marine net pens.

Purpose of the Study:

• To develop and evaluate a novel microscopic bubble generating system for enhancing seawater quality in marine fish farms.
• To assess the system's effectiveness in increasing dissolved oxygen (DO) concentration within net pens.
• To analyze the economic viability and cost-recovery of the developed system.

Main Methods:

• A "microscopic bubble generating system" was installed in marine net pens for red sea bream (Pagrus major).
• Dissolved oxygen (DO) concentrations and water temperatures were monitored across different layers within and outside the net pens.
• System costs, including capital and operation, were analyzed for economic feasibility.

Main Results:

• DO concentrations in bubbling net pens significantly increased by 0.52–0.87 mg/L compared to outside levels, achieving near-saturation.
• Water temperatures showed a slight decrease (0.08–0.12°C) across all layers in the bubbling net pens.
• Micro-bubbles were observed to distribute into deeper water layers, indicating effective oxygenation throughout the water column.

Conclusions:

• The developed microscopic bubble generating system efficiently increases dissolved oxygen concentration in all water layers of marine fish farms.
• The system offers a practical solution for improving water quality in aquaculture, supporting healthier fish populations.
• The economic analysis indicates a rapid capital and operational cost recovery within one year, making it a sustainable aquaculture technology.