Sources : Sturgeon

Pliny the Elder [1st century CE] (Natural History, Book 9, 17; 9, 27): [Book 9, 17] ...the sturgeon [attilus] in the Po, a fish that grows so fat from sloth that it sometimes reaches a thousand pounds; it is caught with a hook on a chain and only drawn out of the water by teams of oxen. And this monster is killed by the bite of a very small fish called the anchovy which goes for a particular vein in its throat with remarkable voracity. [Book 9, 17] In old days the sturgeon [accipenser] was held to be the noblest of the fishes, being the only one with its scales turned towards the mouth, in the opposite direction to the one in which it swims; but now it is held in no esteem, which for my part I think surprising, as it is a fish seldom to be found. One name for it is the elops. - [Rackham translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.10; 7.72): [Thomas descries the sturgeon under the names accipender and sturio.] [Fish 7.10] As Pliny says, the accipender fish was the most noble among the ancients. This fish alone, contrary to the custom of all other fishes, has the scales of the whole body turned towards the mouth. This fish signifies legal experts and clerical lawyers, who generally turn all the protection of the ecclesiastical body, of which they are faithful members, into a contention of words, not caring to notice, because there is no end to words. And while most of them are scrupulous in conscience and have God in mind, they strive to allege falsity instead of truth in the falsity of taunts: Woe to such, and woe again and again! [Fish 7.72] The sturgeon [sturio] is a large fish, which the barbarians call a storam. It lives in rivers waters, and in these it is large and widespread. It cannot live long in ponds, unless it has had a passage to the fresh waters of rivers [Thomas repeats this from the description of the salmon]. It allows little or no food into it body, since the calmness of the air alone is sufficient for its nourishment. Thus it happens that it has a small belly, almost as solid in the place of the belly as in the rest of the body. For although its intestines are very small in relation to its body, the liver is quite large, and the liver itself is so sweet that it can hardly be eaten without an troubles of the stomach. Whence the liver itself, which is contiguous, is usually rubbed with gall, so that the excess of sweetness in liver is moderated by the excess of bitterness in the gall. It lacks a mouth, and that part is closed which in other animals the mouth is found; nor does it have more than a small opening under the throat, closed when it wills, but open to the serenity of the air. In the south they strike more quickly; in the north, however, they blow and settle in the depths. A sturgeon placed in milk lives as long as in water. Freshly caught and eaten, almost all of it passes into the body's nourishment. At the sound of thunder its flesh suddenly rots and corrupts. There is also another fish, called the dannus, which, if hung on a beam, trembles at the sound of thunder. Which is also almost always harmful, and most of all induces fevers. - [Badke translation/paraphrase]