head-and-tail-light \ˌ ̷ ̷ ̷ ̷ˈ ̷ ̷ˌ ̷ ̷\noun alsohead-and-tail-light fish : a small So. American characin fish (Hemigrammus ocellifer) that is translucent green with orange-tinged black-tipped fins and shimmering red eyes and tail spots and is often kept in the tropical aquarium