Fresh water ice. Why? I make it myself as I have an ice maker. We take two 90 litre bins for a big day and we either fill each half with ice or fill one totally. Once we start catching, the fish get killed and go into the ice, once there are three or four, or five we pour some water in the bin to make a slurry.
As we know, ice is pretty cold. Fresh water ice starts to thaw from 0 degrees Celsius upwards. What a slurry does is transmit heat much better than just ice will therefore the fish will cool down faster in a slurry. We don't add enough water to melt all the ice, because then that fish graveyard temperature will start to rise. When we get home we drain the water as the fish is chilled and the ice will keep the fish cold.
When you drain the water it will be cloudy from fish blood, fish poop and slime. I'd rather not leave it sitting in that overnight. Not the end of the world but not the best either.
If possible we fillet the next day when the fish flesh has set and the fish has been through rigor mortis. Plus we like a few beers after fishing and sharp knives and beer isn't usually flash.
Having said that I have two lovely fish fillets from today for dinner tonight that were caught today, thanks to Mars. The flesh was set perfectly and he just used frozen bottles filled with water and sea water added but it's hardly the middle of summer. Yes you can get too fussy and it is one of the few things I am fussy about is chilling fish down.
Salt water flake ice is the best though. Why? Well only my opinion but the big advantage that salt ice has is that it is flaky so it makes a much better contact with the surface of the fish. No need to slurry (that's a backward step IMO) so less risk of transmission of bacteria. As my method works well for day trips I'm all for it. If you're storing fish for longer periods then yes salt flake ice is better.
I dunno about you guys but I don't have affordable access to 90 litres of salt ice, but I can take as much fresh water ice as I want.
I know Matt Watson had a great thing about salt ice and it was all very scientific, apparently salt ice has less bacteria. And I agree, no slurry, less bacteria. I don't claim to have the knowledge that MW has - yes I'm a big fan - so just be careful where you get your salt water from to wash your fillets. Remember most city beaches around the country have very high faecal bacteria levels after heavy rain.
To address that, i don't wash my fillets until they are ready to cook. Trust me, washing them in fresh water just before cooking wont turn them to mush.
I'm not an expert but our fish is pretty good. Commercial guys keep their fish for many days, keep it at 1 degree C and it will be fine. That's around the melting point of fresh water ice.
I guess you can tell it is something I have strong thoughts on
.
I'm keen to hear how others do it, but I've been disappointed so many times with poorly treated fish.