those that are allergic to shrimp may have a problem with krill. ....but the capsules contain a natural antioxidant and are supposed to be better absorbed due to the way the omega3 are chemically connected..the shelf life is longer, supposed to be no burp... Only one company in canada makes Krill oil...and distributes it to everyone else.
Actually foods lower on the food chainhave fewer natural toxins such as mercury and not more.....as the one goes up the food chain, the predatory fish and larger animals etc increase in toxins as they accumulate it in their flesh..
Both Krill and fish oil are carefully tested for mercury pcb's etc...none to speak of...
i still take the plain fish oil...keep it in the fridge..or freeze it...