Fishes along curves and variables sizes

So, i'm really rust in GH, i took some clourses in university but that was 4 years ago and now i can not remember much.

So right now i'm working as a freelance (you see a lot of weird requests under that kind of employment) and someone asked to make a door for their children.(they're are crazy for fishes) with a design of a shoal, bank of Fishes, in it. So the thing, is that i remember some things but i can't make it in order.

-This is the shoal concept that we created or sketched-

-These are the lines that we think can pull off the concept-

The thing is that i want to make something like the drawings a lot of fishes (of different sizes, but in a range of 5-8 cm) but all these fishes are acommodated along the curves (like the second bunch of drawings).

The thing is:

1.- Do i have to draw each curve? or i can draw bunch lines that get deformed when i put a point near of them (i remember that i did something like that in the school) and just playing around until getting something that resembles the concept?

2.- How can i do it in "2D" what i mean is that, i remember doing that (i put a point near of others, and the latter get small or big according of the proximity of the point).

Right now i only have the "door", and populated it with "populate points 2d" but i want to order it. Populate 2d is the correct tool? or do i have to stablish a lot of points with different coordinates?

Thank you for asking such simple questions, but i need help to really start.

Here's the definition that i have right now, do not know if its right.

Here's the definition that i got right now, but im not sure about it.

Thank you very much!. 

Shoal.gh