Executive Summary
Iceland’s aquaculture sector produced 64,417 tonnes of farmed fish in 2025, representing a 17% year-over-year increase according to Statistics Iceland. Arctic char (Salvelinus alpinus) accounted for 5,141 tonnes, cementing Iceland’s position as the world’s largest producer of this premium cold-water species. As the sector expands, feed manufacturers face mounting pressure to deliver pellets with consistent physical quality—particularly water stability and durability—at production volumes that match accelerating farm demand.
This case study examines how one Icelandic aquafeed manufacturer achieved stable output and high customer satisfaction by deploying Liyang Hongyang Feed Machinery’s ring die pellet mill technology, with customized ring die specifications tailored to Arctic char sinking feed formulations.
Iceland’s Aquaculture Growth and Feed Supply Dynamics
The rapid expansion of land-based salmon and Arctic char farming in Iceland has created unprecedented demand for specialized aquafeed. Laxá, Iceland’s primary domestic feed manufacturer based in Akureyri, produced a record 15,000 tonnes of fish feed in 2025—up approximately 3,000 tonnes from 2024. The company’s managing director, Gunnar Örn Kristjánsson, confirmed that annual turnover reached approximately four billion ISK (roughly $29 million USD), while noting the factory still operates below its 25,000-tonne maximum capacity.
Laxá’s product portfolio illustrates the technical demands of cold-water aquafeed manufacturing. Their ECO-LF low-fat formulation, optimized specifically for Arctic char and trout, contains up to 28% fat content with high digestibility. The company also produces ECO high-fat feed (32% fat) for Atlantic salmon and specialized starter feeds for hatchery-stage fish. These formulations require precise pellet density control—sinking pellets that maintain structural integrity during extended immersion in cold water without excessive nutrient leaching.
The Pellet Quality Challenge for Arctic Char Feed
Arctic char are cold-water salmonids that thrive in temperatures between 4°C and 12°C, typically farmed in recirculating aquaculture systems (RAS), flow-through raceways, and tank-based setups. Their feeding behavior demands sinking pellets with specific physical characteristics:
Water Stability: According to industry standards cited by aquaculture feed technology sources, high-quality sinking aquafeed pellets should maintain structural integrity for a minimum of 30 minutes in still water with weight loss not exceeding 8%. For bottom-feeding species requiring longer immersion, this threshold extends further.
Pellet Durability Index (PDI): Export-grade aquafeed must withstand bulk handling, pneumatic conveying, and extended storage without generating excessive fines. A PDI above 94% is generally considered the benchmark for commercial shipments.
Uniform Pellet Size: Arctic char feed typically requires pellet diameters ranging from 2.0 mm for juveniles to 6.0 mm for grow-out stages, with strict size consistency to ensure even feeding and minimize feed conversion ratio (FCR) variation across production cycles.
Nutrient Density: Arctic char formulations demand 40-50% protein content and 15-25% fat, placing significant mechanical stress on pellet mill components during compression. Higher fat content can act as a lubricant during extrusion, potentially reducing die friction and compromising pellet compaction if the ring die is not correctly specified.
The Icelandic manufacturer found that standard ring die configurations—designed primarily for Atlantic salmon feed with different fat profiles—produced inconsistent results when running Arctic char formulations. Pellet hardness varied between batches, and water stability at the 30-minute benchmark occasionally fell below acceptable thresholds, leading to customer complaints about feed wastage and water quality degradation in RAS operations.
Hongyang’s Ring Die Pellet Mill Solution
Liyang Hongyang Feed Machinery Co., Ltd., founded in 2006 and specializing in ring die and pellet mill manufacturing, was approached to provide a customized pelleting solution. Hongyang’s engineers conducted a thorough analysis of the customer’s formulation parameters—including fat content, protein sources, moisture levels, and target pellet specifications—before recommending a tailored ring die configuration.
Ring Die Customization Parameters
The key technical intervention centered on ring die specification:
Compression Ratio: Hongyang’s engineering team calculated an optimal compression ratio based on the formulation’s specific ingredient profile. For Arctic char sinking feed with 26-28% fat content, a higher compression ratio was selected to ensure adequate compaction despite the lubricating effect of elevated fat levels. This parameter is critical: thicker die effective length produces denser, harder pellets suited for sinking feed, while insufficient compression results in soft pellets that disintegrate prematurely in water.
Die Hole Design: Custom inlet conical geometry was specified to optimize material flow into the compression channel, reducing the energy required for extrusion while maintaining consistent pellet density. The die hole diameter configurations supported multiple pellet sizes—1.8 mm, 2.5 mm, 3.5 mm, and 5.0 mm—covering the full Arctic char production cycle from fingerling to harvest.
Material and Hardness: The ring die was manufactured from high-chromium alloy steel using Hongyang’s vacuum hardening process, achieving surface hardness of HRC 60-62 with a hardened layer depth of 1.2-1.5 mm. Full-automatic CNC gun drilling machines with German-imported drill bits ensured precise hole geometry and consistent surface finish inside every die channel.
Pellet Mill Integration: The ring die was integrated with Hongyang’s HYPM series pellet mill, featuring a gear-driven transmission system that maintains consistent torque delivery even under the variable load conditions characteristic of high-fat aquafeed formulations. Unlike belt-driven alternatives that can slip when batch-to-batch formulation variations alter mixture flow characteristics, the precision-ground helical gear drive ensured stable throughput.
On-Site Commissioning and Optimization
Hongyang dispatched a senior engineer to the Icelandic facility for on-site commissioning. Key optimization steps included:
- Initial throughput calibration using the customer’s actual Arctic char formulation rather than standard reference materials
- Steam conditioning parameter adjustment to achieve optimal mash temperature (75-85°C) at the die inlet, balancing starch gelatinization with vitamin retention
- Roller gap fine-tuning to achieve uniform material distribution across the full die face
- Die break-in procedure over a controlled production run to stabilize pellet quality metrics before transitioning to full production
Production Results and Customer Satisfaction
After commissioning and a stabilization period, the customer reported the following performance metrics:
| Parameter | Before Optimization | After Hongyang Solution |
|---|---|---|
| Pellet Durability Index (PDI) | 90-92% | 94-96% |
| Water Stability (30-min weight loss) | 10-12% | 6-7% |
| Fines Content (post-cooling) | 3-5% | Below 2% |
| Production Throughput | 3.2 TPH | 4.0 TPH |
| Die Service Life | 2,500-3,000 tonnes | 5,000+ tonnes |
The improvement in water stability was particularly significant for the customer’s RAS-farming clients. Reduced fines and lower nutrient leaching meant cleaner system water, less frequent filter maintenance, and more consistent feed intake across fish populations. The customer reported a measurable reduction in feed-related complaints from Arctic char farms within the first quarter of operation with the new ring die configuration.
Throughput improvement of approximately 25% allowed the manufacturer to meet growing regional demand without immediate capital expenditure on additional pelleting lines. The extended die service life—attributed to Hongyang’s vacuum hardening process and high-chromium alloy selection—reduced per-tonne die costs and minimized production downtime for die changes.
Industry Context and Broader Implications
Iceland’s aquafeed sector is approaching an inflection point. Laxá’s management has publicly stated that reaching the factory’s 25,000-tonne maximum capacity is “only a matter of time,” and planning for a new production facility is expected to begin within the next few years. The country’s abundant clean water resources, renewable geothermal energy, and strict biosecurity protocols continue to attract investment in land-based aquaculture.
For feed manufacturers operating in this growth environment, pellet mill reliability and consistent output quality are operational imperatives. Ring die performance—compression ratio accuracy, hole geometry precision, material hardness, and wear characteristics—directly determines pellet quality, production efficiency, and ultimately, customer satisfaction at the farm level.
Hongyang’s ability to provide customized ring die solutions—tailored to specific formulations rather than off-the-shelf configurations—addresses a gap that standardized die suppliers often cannot fill. The company’s in-house manufacturing capability, from raw material analysis through CNC drilling and vacuum hardening, enables rapid design iteration when faced with challenging formulations like high-fat Arctic char feed.
Conclusion
The Icelandic Arctic char feed case demonstrates that ring die specification is not a commodity decision but a critical engineering variable that directly impacts pellet quality, production efficiency, and end-user satisfaction. By applying precise compression ratio calculation, optimized die hole geometry, and advanced material hardening to the specific demands of high-fat sinking aquafeed, Hongyang’s ring die pellet mill technology enabled the Icelandic manufacturer to achieve consistent pellet durability above 94%, water stability below 7% weight loss at 30 minutes, and a 25% throughput increase—all while extending die service life by approximately 70%.
As Iceland’s aquaculture sector continues its trajectory toward full-capacity feed production, the technical partnership between feed manufacturers and equipment suppliers like Liyang Hongyang Feed Machinery Co., Ltd. will play an increasingly important role in sustaining quality and efficiency throughout the cold-water fish feed supply chain.
Post time: Jun-20-2026
