Sources : Pungitivus

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.64): The pungitivus [stinging fish] is almost the smallest of all fishes, having its name from the fact that it stings [pungo, sting] with certain thorns. The male is red around the throat, the female is devoid of redness. Both of them have wavy spots. The common people think that these grow without eggs in the waters, and, what is more wonderful, that others are propagated by the eggs of these; whence also this fish is called the mother fish [matrem piscium]. To this they add proofs; for they say that if a new pond is made and no fish are put in, these little fish are found in it the first year, and in the second year fish of a different kind are propagated from the same little fish. - [Badke translation/paraphrase]