How do I compare these variables for a Fishy clone?

I'm playing around, trying to make a clone of Fishy (http://fishy-flash-game.com/)

I'm sure I am looking at this the wrong way. I have a couple of issues going on here.

First of all I find that i have trouble setting the size of my sprites. I want them to maintain the same width/height ratio and I would preferably do that in pixels. Though this is not my biggest problem.

The real problem here is that I somehow cannot compare the size of my enemy instance to the current size of the player. Any help would be greatly appreciated!

In an ideal world, my code would look something like this:

System every x seconds

try this

dl.dropboxusercontent.com/u/14855413/fishy.capx

(copy and paste the link)

So I guess you would like something like:

Enemy on created

Enemy set Instance var Enemysize = random(4,128)

Enemy set size [width = EnemySize, height = EnemySize]

Player on collission with Enemy

if PlayerSize >= Enemy.Enemysize

destroy enemy

else

destroy player

Thank you both for your answers, worked like a charm!