You can more or less consider it a mega fish farm. With the ‘mega’ referring to the filtration system! Its filtration system will also be the focus in this article. If you are also a huge fan of filtration and filtration techniques you will certainly like it. What I have seen there surpassed my wildest expectations!
A while ago, I visited a fish farm located in IJmuiden, situated in the North Holland province, the Netherlands. In this particular farm the very tasteful Yellowtail kingfish (Seriola lalandi) is raised until they reach a consumption size of 2-3 kg, which takes about 9 months. The Yellowtail Kingfish is a schooling, carnivorous, saltwater species indigenous to the Pacific- and Indian ocean.
Until the fish are four months old they face a stocking density of about 5 liter of water per fish, after this period they are stocked in a lower density where they can grow until they reach the desired consumption weight. The fish is mainly used for the preparation of sushi and is shipped abroad. To reach this size within the short time of one cohort (generation), a load of feed is used. The intensive feeding regime leads to a continuous high load of nitrogen in the system which makes the use of a large filtration system necessary.
‘ It was a real ‘feast’ to look at this very intensive filtration system, which besides the fact that it is very cool, is also very necessary seen the fact that on a daily basis 300 kg of feed is used to reach the fish to grow to consumption weight as soon as possible.’
To start with, a mind-boggling four meter high trickling filter with a 56 m2 ground surface is used. These trickling filter have a flow of 600 m3/h running through them. I wasn’t able to photograph the filters from the front because a lot of stuff was in front of them. But when I found out that the ‘stuff’ blocking my view on the trickling units were actually two very large, continuously flushed, drum filters, I, for a moment, completely forgot about the trickle towers.
These drumfilters alone have a 900m3/h capacity. Behind these two beasts, three times two ‘small’ stagnant beds are located filled with Bionet carrier material. Their capacity is 80m3/h with a 12m3 volume per vessel. It was a real ‘feast’ to look at this very intensive filtration system, which besides the fact that it is very cool, is also very necessary seen the fact that on a daily basis 300kg of feed is used to reach the fish to grow to consumption weight as soon as possible.
For the main water supply, water is pumped up from a 140 meter deep spring. Before use, the water is de-ironed and also UV-filters are used to get rid of any pathogens which might inhabit the water (see photo). A large amount of these filters are used to ensure a large enough capacity for the, close to, 500m³ liter of water used to raise the fish.
Probably it is already quite clear from the above-written, I am very impressed and enthusiastic about the farm and its filtration system. I will take some time for it to settle, also giving you the time to realize the sheer size of this farm. But in a couple of days I’ll be back with the second part of the report of this visit to this Yellow Tail farm. Pffff…500 m3/h running through a drum filter…unbelievable isn’t it?!
Text written by Engel Kromhout van der Meer