The smallest animals often play a hugely important role in sustaining nature’s ecosystems. Tiny, hard to find fishes, otherwise known as cryptobenthic are the ocean’s smallest vertebrates. Scientists now believe that these bright colored little fishes – often less than one cm long and weighing as much as a single pea –may be the main food source for corals, and thus the cornerstone of the world’s coral reef ecosystem.
Unlike most other fishes, the young of cryptobenthic fish don’t stray too far from their natal reefs. According to one study, cryptobenthic larvae account for almost 60 percent of the fish biomass consumed on the reefs, thus providing the key source of nutrients for the ocean’s corals. Because these fish can cycle through seven generations a year, their returning young provide a constant food supply to the reefs. If there is one thing these little fishes do well, it is getting eaten.
 Simon Brandl et al. (2018), The hidden half: ecology and evolution of cryptobenthic fishes on coral reefs, Biological Reviews, May, 2019. https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12423