verb - To swim close behind, or slightly to the side, usually somewhere between the hips and ankles, of another swimmer (or swimmers) in order to take advantage of their slipstream, especially in a race.
The cagey veteran was drafting behind the young swimmer throughout the race.
[Middle English draught, act of drawing or pulling, from Old English.]. Synonyms: hang on, follow, drag and free ride.
noun - Draft is a group of fish.
The swimmers passed over a draft of fish as they jumped off the escort boat.