This conjoined twin (polyembryonic) chinook salmon fry was recently caught in a downstream migrant trap. Though we occasionally see fish like this, they are relatively rare and we have not observed them in the wild at sizes any larger than 50 millimeters. Their rarity is likely a result of their high susceptibility to predation because of reduced swimming performance, similar to the fish in our “Not all fish are created equal” post.
Related photos of conjoined tilapia.
Photo source: FISHBIO