Check this:
http://www.biofuelsdigest.com/blog2/200 ... nder-crop/

Could be that the left over mash could be used as tilapia feed and boost the omega-3 levels. The stuff is a weed, requires no cultivation, fertilizer or irregation. It thrives in marginal land with low rainfall of only 10-17" per year, yet yeilds over 100 gallons of biodiesel per acre.