What you will need:

1. Mackerel scraps preferably, any other fish scraps will do
2. Cooking pot
3. Milk bottle or any glass bottle
4. Water
5. Outdoor cooking stove as it will stink

Step 1.

Take a pot and fill it with 2-3 inches of water, depends how many scraps you have.

Step 2.

Put the pot on the outdoor cooking stove and wait till the water is simmering.

Step 3.

Put your scraps gently into the water, otherwise you may get burnt.

Step 4.

Wait for 5-10 mins for the mackerel to cook.

Step 5.

Take your pot off the heat and strain into your bottle. Make sure your bottle isn't thin plastic or it will melt through.