Sources : Bitterling

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.91): The bitterling [venth], as the common people call it, is a fish which in Latin is called aristosus, because of the innumerable bones [aristas] it has. It is the cheapest of all fish. It often lives in fresh waters, but also in those which are salted by the ebb and flow of the sea. The flesh of this fish is armed internally with many and indeed innumerable bones, so that it is inconvenient to eat. Its flesh is cheap and unpalatable, so it is only food for the poor and outcasts. It is caught in this way: the nets are stretched along or across the water, and in front of the nets above the water is an instrument like an arch, so that it floats on the waves. In the upper part of the instrument a small bell [nola] is suspended. Hearing the sound of the bell the fish come in flocks, following the tinkling sound. Because of this they are are caught in large numbers. This is a clear indication that they have the sense of hearing. By this fish are signified those who, although they do not want to mingle with the dances of madmen and choristers, either because they are old, or because they do not know how, or because they are ashamed, yet willingly listen to obscene and indecent things, and where the ringing is of the devil, who takes the form of choristers, they gather more willingly. Let them be careful, then, lest they fall into the devil's nets, and become prey to the vilest demons, who are fishers of the world's sea, and become food for them and full of remorse. The prophet Habakkuk says about these fish and those who fish: Men, he says, are like the fish of the sea; and in a later text: he lifted it all up on his hook, drew it up in his sack, and gathered it up in his net; over this he will kill and exult, as if the prophet had said: of such he will make his feast, and therefore that devil fisherman will kill and exult. - [Badke translation/paraphrase]