The ancient chroniclers of natural history documented as factual a considerable number of extremely strange, mysterious creatures that are exceedingly implausible from a modern-day zoological standpoint.
Few of these, however, can surely be stranger, more mysterious, and certainly more implausible than the giant worm-like eels with vivid blue bodies that were soberly claimed by Ctesias, Solinus, Philostratus, Aelian, Pliny, and several other famous early scholars to dwell amid the dank riverbed ooze of the Ganges and other major rivers in India.
According to Gaius Iulius Solinus (a renowned Latin scholar and compiler who flourished during the 3rd Century AD), these amazing creatures were 30 ft long. However, their dimensions grew ever larger with repeated retellings by later writers, until they eventually acquired sufficient stature – up to 300 ft long now – to emerge from their muddy seclusion beneath the dark cloak of evening and prey upon oxen, camels, and even elephants!
Not surprisingly, this spectacular species of giant freshwater eel has never been brought to scientific attention. True, there are several species of very large sea-dwelling eels, including various morays, that are blue in colour. However, there are none known to science that are of comparable size and colour but which occur in rivers (interestingly, the longest moray of all, the slender giant moray Strophidon sathete, is known from the Ganges and is said to grow up to 13 ft long but is red-grey in colour, not blue). So unless the Ganges giant blue eel simply originated with sightings from Asia of sizable blue marine eels whose correct provenance and dimensions were later documented incorrectly or confused by chroniclers in Europe, then in best angling traditions it is no doubt a classic case of "the one that got away!"