Killing and carrying your catch — the taste is decided at the pier, not the kitchen

Plenty of people find that the fish they caught tastes worse than the one from the supermarket. The reason is almost always that it was neither killed nor chilled. A fish that thrashes itself to death burns through its reserves, spreads blood into the flesh, and warms up. Two hours in a bucket on a summer breakwater is enough to ruin it. The corollary is the useful part: what you do in the first few minutes decides a difference that no amount of care in the kitchen can recover.

Small fish: the ice slurry is enough

For hand-sized fish — horse mackerel, sardines, mackerel, whiting — dropping them into cold seawater beats handling each one individually. Put ice in the cool box, pour in seawater to make a slurry (shioogori), and drop each fish straight in. Do not let fish sit against bare freshwater ice: they take on water and the flesh goes pale and mushy. Keep the ice in a bag, or submerged in the seawater. Enough water to cover the fish is plenty; flood the box and it stops chilling properly.

Over about 30 cm: spike it, then bleed it

• Brain spike: drive a knife point or pick in just behind and above the eye, where the line of the lateral line would meet it. The body stiffens and the mouth gapes when you have hit it.
• Bleed: cut the thick vessel at the base of the gills, then hold the fish head-down in a bucket of seawater for a few minutes, until the water stops colouring.
• Chill: once bled, wrap it in a bag or newspaper before it goes into the cool box. Not in direct contact with ice.
• Ikejime with a nerve wire is a further refinement, not a requirement. Doing the spike and the bleed properly matters far more.

Bleeding makes a mess of a pier. Do it inside the bucket, empty the used water into a drain or over the edge, and wash the concrete down before you leave. Never leave guts or scales behind: it brings crows and smell, and it is what gets ports closed to anglers.

The first half hour at home

Gut the fish the same day. Mackerel in particular can carry anisakis, a parasite that causes severe pain if eaten alive, so if you intend to eat it raw, check the freezing and heating conditions published by Japan's Ministry of Health, Labour and Welfare and decide from there. Red-fleshed fish such as soudagatsuo generate histamine as they lose freshness, and histamine is not destroyed by cooking — so never leave them at room temperature, and if in doubt do not eat them. Squid: remove the innards, pat dry, separate mantle and tentacles, and refrigerate.

Choosing not to keep it

Do not carry home more than you will eat. That is a point about the resource, and also a practical one — fish deteriorating in a fridge helps nobody. Anything you are not keeping goes back into the water immediately, without being killed. And pufferfish do not come home at all: in Japan their preparation requires a licensed handler and is not permitted otherwise. This app does not describe how to prepare them, for any species.