Valencianea fishes filtering sand

This is quite possibly the most surprising thing you’ll see today! All Valencianea fishes have the curious capacity to filter the sand with their mouth. Thus, they continuously clean the substrate where they live and they feed on little microscopic animals that live in between the sand grains. Moreover, they shape the appearance of their habitat just as they like it and this filtering routine is also part of the mating between individuals, who stay together for life. ?