Thank you for your comment!
The fishes are 5 different sized circles connected by revolution joints with a set limit. I used the PixiJS Rope Mesh to draw the fish graphic along the bones.
The animation is based on a simple noise function that adjusts the motorspeed of the revolution joints.
The option to turn of the crt effect is on my todo-list, unfortunately i did not make it in time. ;)
Here is a early test for the fishes.