I've heard mixing bacon grease and fish oil can help make the most of your fish oil. Does anyone have any tips on keeping it in a liquid form so it can be used in an old ketchup bottle or something of that sort to squirt around a set?

I never could figure out how to keep bacon grease in liquid form in cold temps. Fish oil works great to squirt at a set. In late season when its always cold we use the bacon grease in ita solid form and shave aome.off with a knife at the set. The frozen bacon grease shavings will either stay in that solid form or if sun hits them they may melt into the soil or grass and isnt that just like giving it a squirt from a container of liquid grease too?
I've never mixed the two but that's how we handle bacon grease in late season.

I put bacon grease in an old Stanley thermos and it will stay pourable for quite some time depending on temperature. Know of no way to carry it in a squirt bottle.

I mix bacon grease and glycerin, 50/50
Add the glycerin to the grease when it is still warm. Put the mixture in the frig, every 10 minutes or so stir it.
It will stay as a paste as long as it stays cold.
But I don't think you could use a squirt bottle its still a little thick for that.

Wetdog that mix might be best used in a caulking gun type application.

I have had good luck with fish oil and fryer oil mixed

Maybe you can make a holster of some sort to hold the squirter and wear it around your neck to keep it warm?????

Try mixing in mineral oil or as old lure makers call it paraffin oil

Paraffin oil, AKA: Kerosene.