You can fish a perfect day and still eat a soft, dull fish, because the cooler was half full of ice and the lid stayed open. In Kuwait from May to October the air is near forty degrees and the deck is hotter. A fish left in that heat for an hour loses more quality than it gained in the fight.
Work on one to one by weight as a minimum, and two to one in summer. Ten kilos of fish means ten to twenty kilos of ice for a six to ten hour trip. Ice is cheap and it is the only thing on the boat that actively removes heat. Buy it the evening before, not at the ramp at six in the morning when the shop has sold out.
Blocks look serious but they touch the fish in a few points and leave the rest warm. A slurry of crushed ice, seawater and a little salt, about three to one ice to water, flows around every fish and chills it several times faster. Faster chilling is the whole game: the sooner the core temperature drops, the longer the fish holds.
Bleed the fish immediately, cut the gill arch and let it pump out in a bucket of seawater for a few minutes. Gut it on the deck and rinse the belly with seawater, never with fresh water from the tap, which softens the flesh. A gutted, bled fish chills far faster than a whole one and tastes cleaner a day later.
Firm flesh that springs back, bright clear eyes, red gills, no sour smell at the belly. If the belly is soft or the eyes are cloudy, the chain broke somewhere, usually at the first hour. Note it, because the pattern will repeat and it is almost always ice volume.
Log the trip while it is fresh: hours on the water, ice weight, fish count and how the catch held up. Keep that record in the B7R app next to your tides and sea conditions, and after a few trips you know exactly how much ice your box needs in July.
Two bags of crushed ice and a plan cost less than one wasted kingfish. Load the ice, open the drain, shut the lid.
Get the B7R app free on Google Play for tides at Shuwaikh and Shuaiba, sea conditions and your catch log: https://play.google.com/store/apps/details?id=com.q8dm.b7r