The Aquis is a Badnik robot created by Dr. Eggman that appears in various titles in the Sonic the Hedgehog video games. While modelled after a seahorse, the Aquis was not originally designed for underwater use and was made to fly through the air. Its mouth acts as a gun and it flies using the small webbed wings on its sides. It is a persistent enemy as it will usually follow Sonic around and keep harassing him until it is destroyed.
Sonic the Hedgehog 2
The Aquis appears in the Oil Ocean Zone along with the Octus Badnik. Upon sighting Sonic and/or Tails, it will fly towards them and periodically shoot small oily bullets from its mouth gun. In this game, the Aquis almost never stops pursuing the player and will follow them everywhere until it is destroyed. A single spin-jump is enough to defeat it.
An unnamed Badnik closely resembling Aquis appears in the Blue Marine Zone. In this instance, the Aquis functions in the air and also underwater. They move about in a scuttling pattern, firing projectiles at Sonic when he approaches.
Sonic Lost World
The Aquis reappears in Sonic Lost World's Frozen Factory Zone 1. This time around, it does not attack by shooting at Sonic; its gun has been replaced with a vacuum device that can suck up the rings that Sonic has collected. Sonic can destroy the Aquis with a homing attack which will release the stolen rings upon its destruction.
The Aquis returns to Oil Ocean Zone once more in Sonic Mania. Its behaviour and abilities are exactly the same from its first appearance in Sonic 2; it follows the player constantly and shoots at them with small oil bullets.
Sonic the Comic
Aquis only appeared a few times during Fleetway's Sonic the Comic series. Dr. Robotnik commonly deployed them to defend the Oil Ocean Zone and they would harass Sonic by shooting fireballs at him. In the Issue #7 Sonic story "Super Sonic", an Aquis chased Sonic into an oil pool and then ignited it with fireballs. However, Sonic transformed into his invincible, uncontrollable Super Sonic form and went berserk, destroying the Aquis in retaliation.
Aquis did not appear in the Archie Comics Sonic series until 2011 when Dr. Eggman initiated Operation: Clean Sweep. In this tie-in with the classic games, several Aquis appeared to defend the Oil Ocean refinery from Sonic and the Freedom Fighters.