Jetfish are peaceful, herbivorous, aquatic Rahi that use jet propulsion rather than conventional swimming methods. Their sucking mouthparts are used to vacuum their food (almost exclusively seaweed) into their mouths where it is swallowed whole. Much like some birds, since jetfish have no teeth, they also swallow small stones to assist with grinding up their meals inside their stomachs. When danger threatens, their twin jet engines are quite effective at making a speedy getaway.
The jets are the Bionicle "hands". Since they only have an "On" and "Off" setting, jetfish must bank to one side to turn horizontally. They do this by pointing their jets in different directions.
See how they can position their engines in any direction? This is how a jetfish would loop forward.