I first saw these little gems here:
http://www.realsimple.com/food-recipes/recipe-collections-favorites/desserts/edible-art-00100000064492/index.html?xid=checklistnewsletter-01-23-2012
This is the recipe I followed, but I couldn't find white cranberry juice and white grape juice was too much of a yellow-y color. My mom suggested we use Sprite with unflavored gelatin and it worked out great. It didn't taste as sweet as you would expect from jello, but just more of a light refreshing taste.
The recipe also used gum for the weeds, but the only green gum I could find (without going to every store in town) was minty and I didn't want a minty taste in the jello. I found some green Fruit by the Foot and used that, it worked great. I was worried that it would dissolve in the jello overnight, but it only got a little soft and actually made it look a little more authentic.
I found a package of Swedish Fish that had all different sea creatures at our grocery store, so that's what I used for the gummies. Also at our grocery store I discovered Jello has an unflavored gelatin that is meant to be used for soda, it's called Mixchief.
I didn't know if this was any different than the plain unflavored gelatin, but it was more expensive, so I went with the other stuff.
Here is another version that specifically used the Mixchief Jello brand gelatin.
http://www.confessionsofacookbookqueen.com/2011/08/mini-jello-fish-bowls/
I found this one before the party, but I hadn't paid much attention to the actual recipe, just the part about transferring the set jello to another jar to keep the candy rocks from getting mushy. Looking at her pictures though, you can see all the little bubbles in the jello from the soda, so this mix must be a little different. I would do this next time.
Anyhow, here is the recipe that I used.
Edible Jello Aquariums
4 cups Sprite
3 (.25 oz) packets unflavored gelatin
1 drop blue food coloring
Fruit By the Foot Flavor Kickers Sweet-N-Sour
Swedish Fish Aqua Life gummy candy
1. Place 1 cup of the Sprite in a bowl. Sprinkle with gelatin and let sit for 2 minutes. Bring the remaining 3 cups of Sprite to a boil. (in microwave or stove top)
2. Pour hot Sprite over the gelatin mixture and stir until the gelatin is dissolved. Add the food coloring and let cool to room temperature.
3. Cut the Fruit by the Foot into strips resembling weeds. Press them inside 6 to 8 oz. glasses. Dividing evenly, gently pour the gelatin mixture into each cup, leaving tops of weeds exposed. Refrigerate until firm, 2 to 3 hours.
4. Up to 1 hour before serving, use a paring knife to make vertical cuts in the gelatin and insert the gummies. You can put them in earlier, they actually don't dissolve much, but the color bleeds into the jello.