rivulus: found in small streams of tropical America; often kept in aquariums; usually hermaphroditic
killifish: small mostly marine warm-water carp-like schooling fishes; used as bait or aquarium fishes or in mosquito control
accessory vertebral vein: a vein that accompanies the vertebral vein but passes through the foramen of the transverse process of the 7th cervical vertebra and empties into the brachiocephalic vein