What percentage of fish are herbivorous vs. carnivorous?

Question

It appears that the majority of fish we eat are carnivorous, such as salmon and tuna. This got me wondering how common herbivores and carnivores are among fish species. I couldn't find an answer to this question through a cursory search of the internet.

Answer 1

In terms of tonnage, there are 10x the amount of primary consuming fish (fish that eat plants) than secondary consuming fish (fish that eat the fish that eat plants). There are then 100x the amount of primary consuming fish than tertiary consuming fish (the fish that eat the fish, that eat the plant-eating fish).

I came to this conclusion via following the rule of energy transfer through food pyramids. Rule of 10%.