"Eels are mysterious beings. It may be that what are called their `breeding habits' are teleportations... appearances of eels anywhere cannot be attributed to transportations of spawn... The New York Times, Nov. 30,1930... tells of mysterious appearances of eels in old moats and mountain tarns... Eels can travel over land, but just how they rate as mountain climbers, I don't know." -Fort, Books, p595.
Apropos the Victorian eel-zeal (FT194:51), Juvenal's 1878 editor J Mayor claims "Highlanders loathe them" because of their snake-like look, while his classical contemporary C Badham (Prose Halieutics, or Ancient and Modern Fish-Tattle, Parker, London, 1854, p401) bangs on about "the fabulous properties" of this "passionate and ill-conducted fish".
The main sources are Pliny's Natural History (esp. bk9), Athenaeus's Learned Men at Dinner (esp. bks6-7), and Aelian's History of Animals (passim). They often repeat the same information, and often confound the various varieties, albeit Aelian (bk5 ch48) speaks of civil war between congers and morays.
The basic Latin term is anguilla, producing French anguille - "Before skinning it, stun the eel by banging its head hard against a stone" (Larousse Gastronomique). Roman ones were equally proverbi-eel, our `slippery customer' simile being as old as Plautus, Pseudolus, v747.
Eels were famously eaters and eaten. In Homer (Iliad, bk 2l v203), they devour the kidneys and fat of a dead Trojan. Athenaeus tells of them attacking fishermen's boats, also allying themselves on dry land with vipers against humans. Perhaps this is why eel catchers and pedlars were enviably exempt from taxation, also why Boeotians sacrificed giant specimens to the gods. Every writer rhapsodises over their gastronomic appeal, one calling them "the Helen of all feasts," another poetically exclaiming: "Fear death, for when you're a maggot's meal/You cannot then enjoy an eel."
They also offered medical miracles. Poisoned with snake eggs by his wife, an acolyte of Serapis was advised by his god to let a moray bite him, thereby pulling out the infection (Aelian, bk11 ch34).
Size did matter. Reports range from one big enough to fill a cart up to Pliny's (bk9 ch2 para4) 300-footers in the Ganges. Quantity, too; Pliny (bk9 ch39 para76) speaks of "eels massed into shoals, 1,000 in each" in Lake Garda.
Pliny and co. further credit eels with various unique properties, e.g. birth by spontaneous generation in mud, lack of sexual characteristics, and not floating when dead.
A special whip made of eel-skin was used to flog freeborn Roman boys (Pliny, bk9 ch39 para78). "Up betimes, and with my salt eel went down into the parlour and there did beat my boy till I was fain to take breath" - Pepys's Diary, 24 April 1663.One such for use on errant Seychelles wives occurs in Ian Fleming's The Hildebrand Rarity (1960)-"Bond rarely killed fish, except to eat, but there were exceptions - the sting ray."
Another Flemingesque character was Vedius Pollio, punished by Augustus for feeding slaves to his pet lampreys. Cicero frequently (e.g. Letters to Atticus, bkl nos. 19 & 20) ridicules the mania for these. The besotted Licinius assumed the name Murena or Mr Lamprey (Columella, On Agriculture, !! bk8 chl6 para5). A bevy of anecdotes about (e.g.) Crassus, Hortensius, and Antonia have them weeping over the deaths of eels, which in life they had adorned with earrings and necklaces, named, and trained to come when called - fishing for compliments?
"A shower, at Coalburg, Alabama, of an enormous number of eels that were unknown in Alabama... Piles of them in the streets - people alarmed - farmers coming with carts and taking them away for fertilizing material." - Fort, p546
(reprinted with permission of the Author; blame any typically graphic transcription errors on dm)