Product:

https://editor.p5js.org/hershey_zhang/full/OQyaRGmkZ

p5.js Web Editor

https://editor.p5js.org/hershey_zhang/full/g7D1sUPG3

p5.js Web Editor

https://editor.p5js.org/hershey_zhang/full/IGno0yO55

p5.js Web Editor

Inspiration:

Slow Motion Koi Fish Swimming Aquarium Stock Footage Video (100% Royalty-free) 1026786410 | Shutterstock

Process:

Edition 1:

Untitled

sketch.js file in edition 1

Functions & Parameters:

Fish class takes parameter of (position x, position y, horizontal scale, vertical scale, angle (default facing up), stroke, color)
tailMove function takes parameter of (sway frequency (speed), sway amplitude)
finMove function takes parameter of (sway frequency (speed), sway amplitude, offset (of both vertical and horizontal considering the movement as a wave)

Inside the Fish class: