Salmon farms have become more popular in the past several years. Our ever-growing population has increased the demand for salmon which influences their cultivation. In these aquatic farms, the fish live in limited space in open net cages. Parasites such as salmon lice can multiply quickly due to the high density of fish. One possibility to combat lice infestation is to use baths with dilute concentrations of hydrogen peroxide (H₂O₂) as a delousing agent. The salmon are treated in these baths for up to 20 minutes until the lice detach and die.

While it is true that hydrogen peroxide decomposes relatively quickly, it can be deadly for salmon in high amounts. The concentration must therefore always lie within strict specifications during treatment.

This Process Application Note details the online analysis of H₂O₂ in the salmon treatment bath. The 2060 TI Process Analyzer from Metrohm Process Analytics requires less than two minutes per titration analysis. This online process analyzer helps keep the salmon healthy and safe during treatment by permitting more concentration determinations in less time than manual analysis and always guaranteeing the correct H₂O₂ dosage.

The industrial farming of plants and animals for human consumption is nothing new, although generally this is done on land (agriculture). Aquaculture is the equivalent to agriculture in terms of growing animals and plants for food, but farmed from water sources. Salmon farming has grown in popularity over the years, from the coasts of Norway and Scotland to as far away as New Zealand, Chile, and Alaska [1]. The process of growing salmon is contained either in a net or pond and is controlled from egg to market (Figure 1). An unfortunate side effect of holding such a large volume of fish in a contained area is the proliferation of salmon lice (Lepeophtheirus salmonis), which must be killed off (delousing) for a healthy population of fish to survive. The parasites attach to and feed off of the salmon, causing anemia and even death. The lice can spread quickly during the grading and harvesting processes because of the large disturbances caused.

One of the salmon delousing treatments available is hydrogen peroxide (H₂O₂). A diluted bath of H₂O₂ is prepared in which the fish are introduced for up to 20 minutes, and this removes the attached parasites, which can then be filtered from the water. The benefits of using H₂O₂ are numerous – it is easy to purchase, it is a non-medicinal treatment, and it rapidly degrades into water and oxygen as byproducts.

Challenges remain regarding the efficiency of dosing, mixing, and the distribution of H₂O₂ in the salmon treatment tank to prevent overdosing, which can cause oxidative stress in the fish, the bleaching of skin/scales, and even death. Therefore, quick analysis and response times are critical. The Metrohm Process Analytics 2060 TI Process Analyzer (Figure 2) can monitor the concentration of H₂O₂ and be used to control the dose rate accurately into the salmon treatment tank, ensuring that the delousing treatment process runs within specifications. These online process analyzers are currently in use at several salmon farms.

AN-PAN-1029 Peracetic acid (PES) as disinfectant for PET bottles

AN-PAN-1054 Online monitoring of hydrogen peroxide during the CMP process

AN-PAN-1055 Monitoring quality parameters in standard cleaning baths

AN-T-025 Hydrogen peroxide content in aqueous solutions

AN-NIR-095 Quality Control of Hand Sanitizers

Brochure: Fishery & Aquaculture – reliable online, inline, and atline analysis systems for optimizing aquaculture plants

Brochure: 2026 Hydrogen Peroxide Analyzer

• Detect treatment upsets quickly (e.g., incorrect chemical dosing) via automated analysis
• Improved manufacturing efficiency (avoid lower fish yields and harvesting disturbances)
• Monitor multiple treatment baths (up to 10) for more savings per measurement point and results