Fish Tank Birthday Cake Design

by Karen Tack

Fish Tank Birthday Cake Design

How to make a fish tank birthday cake with goldfish crackers and Jolly Rancher fruit chews.


Serves 16




  • 1 (10 by 15-inch) cake
  • 1 can (16 oz) vanilla frosting
  • 1 ½ cups dark chocolate frosting
  • Blue food coloring
  • 1 cup praline crunch sundae topping
  • Mini-colored goldfish crackers (Pepperidge Farm)
  • 2 graham crackers
  • 8 green Jolly Rancher fruit chews
  • 4 spearmint leaves
  • 3 tablespoons sugar


What you’ll need:


  • 2 resealable sandwich-size plastic bags (Ziploc)
  • A serrated knife


Trimming the cake:


  1. Trim the top of the cake and make smooth.
  2. Transfer cake, cut side down, onto a serving platter.


Frosting the cake:


  1. Spoon 2 Tbsp vanilla frosting into a resealable plastic bag.
  2. Spoon the dark chocolate frosting into a resealable plastic bag.
  3. Add enough food coloring to the remaining vanilla frosting to tint it a light blue.
  4. Heat the green Jolly Rancher fruit chews on the microwave for no more than 3 seconds to soften. Roll out the fruit chews and cut them into seaweed shapes as pictured.
  5. Sprinkle a little sugar onto your work surface to prevent sticking.  Roll the spearmint leaves out in the sugar. Cut the flattened green leaves into long oval shapes and twist, as pictured.
  6. Using a serrated knife, cut the graham crackers into tower shapes.
  7. Spread the blue frosting over the top and the sides of the cake. Make smooth.


To complete the decoration:


  1. Press the praline crunch in an uneven line along the bottom edge of cake for the sand.
  2. Press the graham cracker tower, the seaweed-shaped fruit chews, the twisted spearmint ovals, and the goldfish crackers all over the cake.
  3. Snip a very small corner from the bags with the vanilla and dark chocolate frostings. Pipe white dots above the goldfish crackers for bubbles.  Pipe dark chocolate eyes onto the goldfish crackers.
  4. Enlarge the cut corner in the bag with the dark chocolate frosting to ¼ inch. Pipe a border with the chocolate frosting to create the outline of the fish tank.


Cake Anatomy:


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