User blog comment:Kyz99/Krogan Vs Yahg/@comment-4237253-20120304202038/@comment-180.252.94.196-20130710010928

Going back to first encounter between Citadel Envoys and Yahg: the Yahg took offense at their self-perceived insult over the Citadel's non-submissive approach and killed them all.

This shows well that the Yahg (with exception of the Shadow Broker), are mostly short sighted species and way too big ego and inability to perceive anything greater than themselves, they even lack curiosity to at least be patient and investigate further.

With exception of SB, the Yahg are simply (stupid) space bullies. The Krogan however is like space mongols. There's no comparison, both in direct battle and in prolonged war, Krogan will wipe out Yahg, it's just a matter of how and when.