The ballyhoo or bally, Hemiramphus brasiliensis, is a baitfish

Bait fish

Bait fish are small fish caught for use as bait to attract large predatory fish, particularly game fish. Species used are typically those that are common and breed rapidly, making them easy to catch and in regular supply. Examples of marine bait fish are anchovies, halfbeaks such as ballyhoo, and...

 of the halfbeak

Halfbeak

The halfbeaks are a geographically widespread and numerically abundant family of epipelagic fish inhabiting warm waters around the world. The family Hemiramphidae is divided into two subfamilies, the primarily marine Hemiramphinae and the freshwater or estuarine Zenarchopterinae...

 family (Hemiramphidae). It is similar to the Balao halfbeak

Balao halfbeak

The Balao halfbeak, Hemiramphus balao, is an ocean-going species of fish in the family Hemiramphidae. It was first described by the French naturalist Charles Alexandre Lesueur in 1821.-Description:...

 (Hemiramphus balao). Ballyhoo are frequently used as cut bait and for trolling purposes by saltwater sportsmen.

Ballyhoo can also be seen above the waters skimming the surface to escape from their predators. The appearance is similar to skipping stones on the water.

Ballyhoo is also used in colloquial American English to refer to brashness or flamboyance.
The term Ballyhoo is used to indicate that one is using any means necessary to inflate an object or idea to a status to which it does not rise.