Preheat the oven to 190°C.
Place the washed potatoes into a saucepan. Add the milk to just cover the potatoes and bring to the boil over a gentle heat. Once the milk has reached a gentle simmer, add the fish to the saucepan and cook gently for another 12 minutes, or until fish starts to flake. Once fish and potatoes are cooked, remove with a slotted spoon and set aside in a bowl, leaving the milk in the saucepan. Mash the fish and potatoes with a fork.
Place the corn in the milk and cook for 10 minutes, then strain and add to the fish and potatoes. Reserve the cooking liquid for later.
To the fish mix, add the egg yolks, 1 serving of AptaGrow powder, mozzarella and a little salt. Mix together well. If the mix is a little dry, add some of the reserved cooking liquid.
In another bowl, whisk the egg whites.
Place rice cakes into a blender and whiz until you achieve fine crumbs. Tip into a separate bowl.
With the fish mix, make 12 small balls (the size of a ping pong ball) and place on a greased tray. Place in the fridge for 15 minutes to cool.
Remove from the fridge and dip each ball into the egg whites, then the rice cake crumbs. Place back onto the greased tray and flatten into a pattie. Repeat with the remaining balls.
Drizzle with a little oil then bake in the oven for 15 to 20 minutes, or until golden, turning halfway. Leave to cool slightly before serving.