I think experimenting is one of the trill of this hobby. I think you cannot go wrong feeding them these products. The manufacturer goes through extensive testing before putting it on the market. As for ranchu, high protein diet is very important especially if you are feeding them dried food.

Look for products with added amino acids. For normal GF protein content of around 40% to 45% is OK, but for ranchu try to go for 50% and above.

Spend time observing your ranchu and see how they response to your feeding. During the first year or so, they should grow by about 1 cm a month plus and minus.

Water condition is more important than the feed. Practise good housekeeping for your tubs.