As a vital component of China's aquaculture industry, freshwater aquaculture encompasses various models such as pond aquaculture, reservoir aquaculture, and industrial recirculating aquaculture systems (RAS). The main cultivated species include grass carp, silver carp, sea bass, California sea bass, and loach. Compared with mariculture, freshwater aquaculture does not face extreme conditions like high salinity and strong water pressure, but it has challenges such as significant differences in water transparency, uneven stocking density, and easy spread of diseases. With its flexible adaptability and precise monitoring capabilities, underwater aquaculture cameras have become a core tool for transforming freshwater aquaculture from "experience-based management" to "precision management". Their specific applications can be elaborated from the following four scenarios:
1. Pond Aquaculture: Addressing Pain Points of Traditional Extensive Management
Pond aquaculture is the most mainstream model in freshwater aquaculture. Traditional management relies on manual methods such as "observing water color" and "fishing for samples" to judge the aquaculture status, which has large errors and is prone to delaying risk response. Underwater aquaculture cameras can achieve multi-dimensional monitoring in this scenario:
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Monitoring Growth of Fry and Adult Fish: Cameras installed in the upper-middle, middle, and bottom layers of the pond can clearly observe the growth status of fish in different water layers. For example, grass carp, as middle-bottom dwelling fish, the camera lens can capture their body size and swimming vitality to assess growth uniformity. If some grass carp are significantly smaller than their counterparts, feeding strategies can be adjusted promptly (e.g., increasing targeted bait input). For benthic fish like loach and rice field eel, cameras (some models with turbid water penetration function) can penetrate turbid water to observe their burrowing habits and feeding enthusiasm, avoiding damage to the habitat caused by traditional "pond-turning inspections".
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Control of Residual Bait and Water Quality: Accumulation of residual bait in pond aquaculture easily leads to water quality deterioration (such as excessive ammonia nitrogen and cyanobacterial blooms). Cameras can capture real-time images of residual bait at the pond bottom. If a large number of feed pellets are found precipitated without being consumed by fish, the feeding amount must be reduced immediately. Meanwhile, by observing water transparency through the lens (e.g., whether the water turns green due to algae reproduction or whether floating films appear), combined with data from water quality sensors, aerators can be activated or water changes can be conducted in a timely manner to prevent fish from "pond die-off" due to oxygen deficiency. For instance, during the high-temperature summer period, if cameras capture fish gathering and swimming near aerators, even if the dissolved oxygen meter data does not reach the critical value, aeration intensity can be increased in advance to avoid nighttime oxygen deficiency risks.
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Early Warning of Diseases and Pests: In the early stage of fish infected with bacterial diseases such as gill rot and red-skin disease, symptoms like slow swimming and body surface congestion appear. High-definition camera lenses can capture these subtle abnormalities, detecting problems 1-2 days earlier than manual visual observation and gaining time for disease prevention and control. In addition, the lens can monitor whether pests (such as rats and snakes) around the pond enter the water to prey on fish, triggering early warnings and taking repellent measures promptly.
2. Industrial Recirculating Aquaculture Systems (RAS): Adapting to High-Density Precision Management Needs
Industrial RAS is a high-end model in freshwater aquaculture, characterized by high density and high controllability, which has extremely high requirements for real-time monitoring of water quality and fish status. Underwater aquaculture cameras play a core role in this scenario:
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Monitoring Fish Behavior and Water Flow Adaptability: The water flow rate in RAS tanks needs to match fish habits (e.g., California sea bass is suitable for slow water flow). Cameras can observe the swimming trajectory of fish. If fish are found continuously swimming against the current with high energy consumption, the water flow rate needs to be adjusted. At the same time, the lens can determine the clustering of fish to avoid local over-density leading to oxygen deficiency or bait competition, ensuring each fish has sufficient living space for growth.
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Precision Feeding and Dead Fish Removal: The water purification capacity of RAS is limited, and overfeeding easily burdens the system. Cameras can record the entire feeding process of fish. For example, California sea bass will attack bait quickly when feeding; if the lens shows that bait is not consumed in time and flows into the filtration system with water, the feeding amount must be reduced immediately. Some high-end cameras are equipped with AI recognition functions, which can automatically identify dead fish (usually floating or stationary at the tank bottom) and trigger alarm signals. Staff can promptly remove dead fish to prevent water pollution and subsequent disease outbreaks, ensuring the stable operation of the RAS.
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Monitoring Status of Filtration Systems: Blockage or failure of filtration equipment (such as biological filters and sedimentation tanks) in RAS will directly affect water quality. Cameras can be installed at the water inlets and outlets of filtration systems to observe the impurity content in water (e.g., whether there is a large amount of organic debris) and the status of filter media (e.g., whether it is caked). This reminds maintenance personnel to clean or replace the filter media in a timely manner, avoiding water quality collapse caused by filtration system failures.
3. Reservoir Aquaculture: Solving the Difficulty of Large-Scale Monitoring
Reservoir aquaculture covers a large area and has deep water, making it difficult for traditional manual inspections to cover the entire area. Underwater aquaculture cameras can achieve comprehensive monitoring through a combination of fixed-point and mobile methods:
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Cage Aquaculture Monitoring: Reservoir cage aquaculture is mostly distributed in different water areas. Cameras can be installed on the inner walls of cages to observe the feeding status of fish (such as silver carp and bighead carp) and the integrity of cage nets in real time. If cage net damage is found (e.g., torn by floating objects), it can be repaired promptly to prevent fish escape. At the same time, the lens records the water flow rate around the cages to avoid fish stress or bait loss caused by excessive water flow.
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Assessment of Fish Distribution and Resources in Large Water Areas: When wild fish and farmed fish are co-cultured in reservoirs, cameras mounted on underwater mobile platforms (such as underwater robots) can take photos and count fish in different areas, evaluating the population quantity and growth status of fish. This provides data support for adjusting stocking density and formulating fishing plans in reservoir aquaculture, avoiding ecological imbalance caused by over-aquaculture.
4. Fry Rearing: Safeguarding the Critical Early Growth Stage
Freshwater fry rearing (such as fish fry and shrimp fry) is the foundation of the aquaculture industry chain. The fry are tiny and sensitive to the environment, and underwater aquaculture cameras can achieve precise observation:
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Monitoring Fry Vitality and Initial Feeding: Newly hatched fish fry (e.g., grass carp fry) are only 2-3 mm in length. With macro shooting function, cameras can observe their swimming ability (e.g., whether they can flexibly avoid obstacles) and initial feeding status (e.g., whether they actively ingest initial baits like rotifers). If fry are found to have weak swimming ability and no feeding behavior, the rearing water temperature (e.g., increasing to the suitable range) or bait formula can be adjusted promptly to improve fry survival rate.
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Controlling Stability of Fry Rearing Environment: The water quality of fry rearing tanks needs to be stable (e.g., pH 7.5-8.5, water temperature fluctuation not exceeding 2℃). Cameras can observe abnormal bubbles in the water (e.g., methane bubbles generated by sediment fermentation) and whether there are pest organisms (e.g., cyclops preying on fry). Combined with water quality monitoring equipment, environmental parameters can be adjusted in a timely manner to provide a suitable growth environment for fry.
Summary of Application Value of Underwater Aquaculture Cameras in Freshwater Aquaculture
In the field of freshwater aquaculture, underwater aquaculture cameras have achieved a management transformation from "passive response" to "proactive prevention" by breaking through the visual limitations of water bodies. On one hand, through real-time monitoring of fish growth, water quality, and diseases, they reduce labor costs (one camera can replace the daily workload of 2-3 inspectors) and lower feed waste (precision feeding can reduce feed loss by 10%-15%). On the other hand, by providing early risk warnings and optimizing the aquaculture environment, they improve fry survival rate (by 8%-12%) and adult fish quality, contributing to the green, efficient, and sustainable development of the freshwater aquaculture industry.
