Where are you located?
I would just check my local fish shops for pellets and flakes. Check the label for the protein/fat content.
But does it have to be pellets or flakes (processed foods)?
For high protein food, try frozen blood worms or blackworms. If you were eating fish for dinner at home, you can drop in a small sliver of that fish before is was cooked. Prawns used for bait is also perfect for high protein foods for these Thai Micro crabs. High protein foods means meat. But stick to seafood only.
As for high fat food, try vegetables. Here are the top 20 veges ordered according to grams of fat per cup:
Soybeans: 11.52 grams
Corn: 2.23 grams
Kidney Beans: 1.54 grams
Black Beans: 0.9 grams
Northern Beans: 0.8 grams
Cooked Lentils: 0.8 grams
Cooked Peas: 0.6 grams
Broccoli: 0.5 grams
Unpeeled Zucchini: 0.4 grams
Tomatoes: 0.36 grams
Carrots: 0.31 grams
Cauliflower: 0.3 grams
Red Bell Peppers: 0.3 grams
Kale: 0.3 grams
White Potatoes: 0.21 grams
Butternut Squash: 0.18 grams
Collard and Turnip Greens: 0.17 grams
Pumpkin: 0.17 grams
Spinach: 0.12 grams
Cucumber: 0.12 grams