(consistancy is always good), while the sliders just allow you to say how much you like each fish.
I am being consistant with the Macintosh OS X interface and I am being consistant with the After Dark series of screen savers. I think if you ask Jim, he will tell you that the drop-down menus were a kludge and never intended to be the "definitive" or permanent way of selecting fish.
With just the sliders its not easy to distinguish between the option of having 7 fish but selecting all 7 from your favourite set of 3 and only having 3 fish in the tank. Is this even possible. With the sliders as shown if you want less than 7 fish you have to make a choice about what those fish are going to be (i.e. you can't have a random choice of less than 7 fish). You would need a separate box to say how many fish you wanted to show. Or am I completely missing something here.
Pick a few fish on the left from the drop-downs, set all the random fish on the right to "NEVER."
I really am not sure why you are being so emphatic about his design when you have twice had questions about how to configure fish a certain way with it. The idea of a good interface is that everything seems obvious. You shouldn't have to ask any questions about how to do things.
I think anyone who stumbles across the Aquarium as a new product (having never seen 99L or 1.0) will go to the Fish selection page and see pictures of the fish they like and drag the slider to the right on each fish he/she likes and drag the slider to the left on fish he/she doesn't like.
No drop-downs, no checkboxes, no nonsense.
Again, these are just my ideas, but I know a thing or two about user interfaces. I really would like to see a design that improves on mine and is thinking outside of the box. The drop-downs seems like a dogmatic attempt to stick with the 99L/1.0 way. I'm sure there's an even better way to do this than my idea.