Made my own fish oil for trapping for years. No reason to buy fish oil when
you can make it yourself.
You'll need a 5 gal. bucket w/lid, and about 3' of 1/2" hose.
Get yourself a mess of either trout or catfish (carp will do in a pinch).
Gut them, then chop the fish into 1" chunks, and drop them into the
bucket. Gonna take a mess of fish, but fill the bucket up about half
way.
Put the lid on (tight!), then drill a 1/2" hole in the lid and insert the
hose about 6". The hose will carry out the expansive gasses that are
created during the rendering process.
Set the bucket out where it gets full Sun all day. Preferably, chose
a spot that is downwind of your residence.
Leave it there in the Sun for a few weeks. (yes, weeks)
After a few weeks, pick a windy day (or use a strong fan) and remove
the lid.
Take another 5 gal bucket and place a 30 mesh classifier on top, then
dump the contents of the bucket into the strainer. Let is strain/drain for
an hour or more. What drains through is 90% oil, and use a turkey baster
to draw it off, then save it in a gallon container.
You can either bury the decomposing fish matter (blend into your garden?)
or you should dump it far, far away from home. That, or pick someone you
truly dislike and hide it in the trunk of their car. ...
[CAUTION: Be sure to stay up wind 'cause this stuff will make your eyes water
and your gut wretch...but...it's pure fish oil.]
A gallon of that oil should go a long ways.
I've thought of a way I might be able to test this "oil method", and if I can
get a couple good days back-to-back in the next few weeks I might give it a go.