First a small disclaimer: I am far from a professional chef, and this is quite a long post. Any tips, tricks and constructive criticism is more than welcome!
Over the last few weeks, I have experimented with aging fish. I have look around on the internet, but its difficult to find any clear and reliable explanation of techniques and the process behind aging fish. So I would like to take this opportunity to share my (admittedly very limited) experience, and ask for any input the almighty Reddit may have.
My process started by buying the freshest fish I could find. This meant obtaining access to a wholesaler, and asking them for fish that was just killed. I ended up buying a kingfish (known in Japanese as hiramasa) farmed locally, that was super fresh and was stored without the guts.
One fresh looking kingfish, without fins
Red gills
I immediately started by drying the cavity of the fish and removing the scales. After, I filleted the fish by taking off its head (which turned into delicious grilled collars later that evening), leaving one side of the fish on the bone.
The filleted side turned into delicious fresh sashimi for the evening, while the part on the bone was prepared for aging by wrapping it in tea cloth. I placed the wrapped fish on a wire rack in my fridge, and attached a thermometer to monitor the temperature. The temperature remained between 1-3 degrees Celsius during the aging period (7 days).
Sashimi made on the day of the fish purchase
Fish before entering the fridge
Over the next week, I turned the fish every twelve hours and occasionally took the fish out of the fridge to check if there were any funky areas or weird smells.
After 7 days in the fridge, the fish looked like this when it was taken apart:
Straight out of the fridge, started incision on the tail
Top loin with a nice amount of fat
Side shot
Finished sashimi of 8 day aged kingfish
Close up of sashimi
The most important takeaways for me are:
Aging this fish improved the flavor of the fattiest part (the belly) the most, and gave it a lot stronger flavor that lasted in the mouth for quite a while
The texture of the top loin was greatly improved, and became more dense yet more tender as well
The bloodline needs to be removed a bit more as it was a little bit dried out, or the fish needs to be aged whole to prevent this
It is fine to keep fish in your fridge for 7 days (I was a little bit hesitant upon the first bite...)
Next time I want to try aging the fish hanging up by its tail
I am happy to hear your experiences with aging or curing fish!