I just bought a used boat and it has a live well, so, I will use that some. But I have made many a fishing trip when I put the fish in the ice chest with ice immediately upon the catch. The colder the fish when cleaning, the less messy it is to fillet.

 

I have filled up gallon jugs that sweet tea comes in (like a milk jug) and also 2 litre coke bottles. Fill them up but not all the way, as the ice will expand. These will keep the fish cool but I don't know about cold. It seems you need ice in there. Preferably crushed ice but that's too expensive if you fish a lot. I recently bought some plastic shoe boxes at the dollar store for $1 each. They work great! You get a top for it but you don't need the top. Fill it about 1" from top. Makes a shoe box chunk of solid ice. Solid ice lasts longer. You can chop it with an ice pick but it will melt faster and be carefuly, you can go to the plastic and punch a hole.

 

Have you found any secrets to putting them on ice quickly?

Keep them in fresh water and alive in live well when fishing. Ice them in a cooler on way home. They will fillet like a dream. Taste better too.

If you're keeping fish for the table, don't let them swim around in a livewell. Stressed fish = poor table fare. 

 

As soon as you land fish, bleed them out into a bucket of water (cut the gill, but not too deep; heart needs to pump out the blood), ice them down, fillet when you get home. 

Gross! Never put icing on a fish, icing belongs on cake.