In your opinion, what fish makes the best quality oil and has a good yield to it. to be clear I am mostly (not exclusively) talking about smaller fish such as shad, bluegill, perch, or other fish of that size.

Will you be sun rendering these fish?

Carp?

Yes

That typically makes too thick of an oil

Not sure what your using it for, but if using it in predator formulations the type of fish makes a difference on attractiveness.

Im with Yes sir so far on this. Need to know its final intended use.

i would be using it as a base in lure formulations

I would have to go with trout or a clean white fish. Herring would be my 2nd choice.

I agree with E.J. I would go with sun rendered trout.