"Non-Intimidating Surveillance": Can It Be Achieved? Fish-Shaped Robots Pave the Way for Precision Aquaculture

A robot disguised as a fish has quietly begun swimming into the future of aquaculture

When people hear about robots inspecting underwater fish farms, they might imagine a machine resembling a small submarine. It would have propellers spinning, lights illuminating, and cameras checking the condition of nets and fish.

However, the focus this time is on a more "fish-like" robot.

The experimental model "UJIFISH-I," developed by CIRTESU, the Center for Underwater Robotics and Underwater Technology at Spain's Universitat Jaume I, is a modular fish-shaped robot designed for net inspection, water quality monitoring, and sensor deployment in fish farms. Its main feature is not just its fish-like shape. It swims by undulating its body like a fish, aiming to reduce elements like propellers and strong lighting that can stress the fish.

In aquaculture, it is essential to continuously monitor the health of fish, net damage, water temperature, dissolved oxygen, and salinity. If a net has a hole, fish can escape. If water quality deterioration is noticed too late, it can lead to poor growth or mass mortality. However, if the inspection itself stresses the fish, it defeats the purpose.

Traditional underwater robots and diver inspections may be efficient for humans, but they are an intrusion for fish. The sound of propellers, sudden water currents, strong lighting, and the movement of approaching machinery are not insignificant stimuli for underwater creatures.

UJIFISH-I aims to reduce this "stress for surveillance." Instead of the robot approaching the fish school, it blends into the environment with fish-like movements. It quietly gathers necessary information while minimizing loud noises and turbulence. This has implications not only for the efficiency of aquaculture but also from the perspectives of animal welfare and environmental impact.

Learning from fish movements, a propeller-less underwater robot

UJIFISH-I is designed as a biomimetic, or bio-inspired, robot. It uses undulatory motion similar to fish swimming for propulsion. This helps to minimize mechanical noise, water disturbance, and physical impact on the surroundings.

While propeller-driven propulsion is common in underwater robots due to its relatively simple structure and ease of control, it generates noise and turbulence. When operating near farmed fish, these stimuli cannot be ignored. In densely populated aquaculture environments, if fish exhibit escape behavior or the school is disturbed, it becomes a stress factor.

By incorporating shapes and movements suited to adult fish, UJIFISH-I aims to achieve smoother fluid dynamics. A robot that swims like a fish is not just for show; it is an engineering response to practical challenges regarding how to move underwater and how little to disturb the surroundings.

Additionally, it is equipped with a panoramic vision system with a 180-degree field of view to capture underwater images. It can operate at depths of up to 20 meters. The range for remote operation is up to 150 meters vertically and 500 meters horizontally. It supports both cable and acoustic modem communication, allowing for flexible use depending on the conditions of the fish farm.

From net inspection and water temperature measurement to sensor deployment

In managing fish farms, it is important not only to observe the fish but to understand the entire surrounding environment.

UJIFISH-I is equipped with sensors that continuously measure water temperature and depth. It is also designed to integrate additional sensors for measuring salinity, pH, dissolved oxygen, and various gases. This makes it more akin to a mobile platform for collecting underwater data in fish farms rather than a standalone robot.

A particularly noteworthy feature is its ability to transport and deploy sensors and auxiliary components to specific locations. This allows the robot not only to observe but also to deliver measuring equipment to necessary points within the fish farm.

For example, if a change in water quality is suspected around a particular net, the robot can move there and deploy additional sensors. Or, if there is a possibility of damage to part of the net, it can be confirmed with panoramic images. In situations where it is dangerous for divers to dive, the robot may be able to substitute for the work.

The research team has confirmed the functional feasibility of the robot through control tests for net inspection, remote operation, data collection, and sensor deployment. High mobility and reliable target detection were also demonstrated.

The broader trend of precision aquaculture

The background of this robot is the global trend toward "precision aquaculture."

In agriculture, precision farming, which uses sensors, drones, AI, and satellite data to meticulously manage crop conditions, is already widespread. Similarly, in aquaculture, there is a growing movement to use data to understand fish behavior, water quality, feeding, disease signs, and net conditions, aiming for more efficient and sustainable operations.

Aquaculture is becoming increasingly important for the world's food supply. As it becomes difficult to rely solely on natural fisheries, expanding aquaculture is essential for the stable supply of seafood. However, there are many issues to address, such as overcrowding, disease, waste, feed, and the impact on ecosystems from escaped fish.

Therefore, there is a demand for technologies that monitor fish farms more precisely and with less impact. Robots like UJIFISH-I could play a part in this.

The key point is that "automation" does not only mean reducing human labor. Underwater inspections can be dangerous for workers due to currents, poor visibility, low temperatures, contact with equipment, and long working hours. If these risks can be replaced by robots, human safety will also increase.

At the same time, if fish can be monitored in a way that minimizes their burden, aquaculture can move toward quieter management. Underwater robots can serve as tools for efficiency and for reducing fish stress and environmental disturbance.

Reactions on social media and online: Interest shifts from "cute" to practicality

Given that the article has just been published, there has not yet been a large-scale discussion on social media within the observable range. On Phys.org, at the time of publication, there are hardly any comments or shares. However, it has already been featured on science news aggregation sites and Chinese-language news aggregation sites with the theme of "robotic fish inspecting nets and water quality while reducing aquaculture stress."

In the Spanish-speaking world, it is notably spreading as local media and university-related news. On Facebook, it has been confirmed that Spanish radio station accounts are sharing this topic. The focus of the reaction is closer to practical interest in "how to safely and environmentally monitor aquaculture" rather than flashy future technology.

Additionally, on bioengineering news sites, the share count on SNS share buttons shows the number of shares on Facebook and X. Although the numbers do not indicate a major buzz, as a specialized news item, it is beginning to reach multiple reader segments, such as robotics, aquaculture, and environmental consideration.

When this type of technology spreads on social media, reactions generally fall into two categories. One is the visual amusement of "robotic fish blending into real fish schools." The other is skepticism about implementation, such as "can it really reduce fish stress," "is it cost-effective," and "how to retrieve it if it breaks down."

Currently, detailed critical discussions like the latter are not yet widespread. However, as this technology approaches practical application, issues such as cost, durability, maintenance, data management, and long-term impact on fish will inevitably arise on social media.

Challenges: Autonomy, operational time, cost

UJIFISH-I is a promising prototype, but it is not yet a finished product ready for use in fish farms worldwide.

The research team itself has identified autonomy, operational duration, and improved sensing capabilities as future challenges. In particular, integrating an artificial buoyancy system for stable operation at greater depths, i.e., active buoyancy control, is a future development theme.

For underwater robots, batteries and communication are significant constraints. Unlike aerial drones, which can easily communicate via radio waves, underwater communication often relies on acoustic communication or cables. The transmission of video data, position control, obstacle avoidance, and safe movement within fish schools involve multiple technologies for practical application.

Moreover, for aquaculture operators, cost-effectiveness is more important than technological novelty. If the introduction cost, maintenance expenses, repair during breakdowns, personnel required for operation, and integration with existing equipment do not fit the field, even the most advanced robot will struggle to gain traction.

Additionally, even if fish-like movements reduce stress in the short term, how fish respond to long-term operation is another issue. Reactions may vary depending on the fish species. Salmon, sea bream, sea bass, tilapia, and other farmed fish have diverse ecologies and breeding environments. How to extend the results from experimental tanks and port facilities to actual large-scale fish farms will be key in the future.

As robots get closer to fish, human responsibility is also questioned

Fish-shaped robots are visually approachable. The sight of machines swimming underwater is futuristic and somewhat humorous. However, their essence is quite realistic.

This relates to the question of how to make food production sites sustainable. Humans raise fish and use them as food. In this process, how do we protect the health of the fish? How do we minimize environmental impact? How do we ensure the safety of workers? To what extent do we integrate data and robots into the field?

UJIFISH-I is one technological approach to this question.

Until now, the primary role of underwater robots has been to "go where humans cannot" and "replace dangerous tasks." In the future, in addition to these roles, the design philosophy of "not startling living creatures" and "not disturbing the environment" will become important. Underwater, quietness will also become part of performance.

Future robots working in fish farms may not be machines that powerfully advance but rather entities that swim in harmony with their surroundings. UJIFISH-I suggests that robots can become tools that learn from natural movements and integrate into the environment, rather than tools that dominate nature.

Of course, this is still a technology in the research stage. It will take time to become practical. However, the concept of a robot that inspects nets, measures water quality, and deploys sensors while reducing fish stress is highly suggestive for considering the future of aquaculture.

In future fish farms, humans, fish, sensors, AI, and fish-shaped robots may share the same waters. What will be important then is not just how much data can be collected, but how quietly and with how little burden on living creatures management can be conducted.

The fact that robots resembling fish have started swimming is not a small piece of news for the fisheries industry. It is also a sign that food production technology is gradually shifting its focus from "efficiency" to "coexistence."

Source URL

Phys.org: Overview, performance, sensors, and stress reduction in farmed fish regarding UJIFISH-I.
https://phys.org/news/2026-04-robotic-fish-prototype-aquaculture-stress.html

EurekAlert!: Announcement content, paper information, research funding, test locations, DOI, etc., by Universitat Jaume I.
https://www.eurekalert.org/news-releases/1125448

ScienceDirect: Publication information for the paper "UJIFISH-I: A modular and bioinspired robotic fish for inspection, hybrid teleoperation and sensor deployment in aquaculture."
https://www.sciencedirect.com/science/article/pii/S0029801826007511

Universitat Jaume I: News publication information from the research institution.
https://www.uji.es/com/investigacio/arxiu/noticies/2026/4/ujifish/

Buzzing: Confirmation of publication on overseas science news aggregation sites. Used to understand reactions on SNS and news aggregation.
https://www.buzzing.cc/

Onda Cero: Introduction article by Spanish-speaking media.
https://www.ondacero.es/emisoras/comunidad-valenciana/castellon/noticias/uji-desarrolla-pez-robotico-modular-acuicultura-que-reduce-estres-peces-mejora-monitorizacion-submarina_2026042269e8beac16cd5c2d46680a24.html

Onda Cero Castellón Facebook post: Example of sharing on Spanish-speaking SNS.
https://www.facebook.com/ondacerocastellon/posts/la-uji-desarrolla-un-pez-rob%C3%B3tico-modular-para-acuicultura-que-reduce-el-estr%C3%A9s-/1568024911990064/

Bioengineer.org: Confirmation of reposting and share count on a specialized news site.
https://bioengineer.org/modular-robotic-fish-prototype-developed-at-universitat-jaume-i-to-minimize-stress-in-aquaculture/