"Common" names and scientific names.

If a fish does have a common name, it's sensible to use it: "Neon Tetra." Sure, what else? But not all fishes have genuine common names. What would you do, if what you thought were Neon Tetras were actually Paracheirodon similans; would you be calling them "False Neon Tetras?" Would anyone know what fish you meant?Common names work best when you're dealing with common species, and never come upon any others. If you only knew one fish in the genus Tropheus, for instance, you could call it a "Trofe" and never get confused. Sentimental democrats strain after fresh-minted, "unCommon" names to show us how non-elite they are. They may succeeed in demonstrating their social correctness well enough, but often we need a translation to know what fish they're talking about.
 
Birdwatching began as a largely anglo-speaking sport, and English-language "common" names for every bird species seen in North America have been invented and codified in the guides. A new development among birdwatchers is that they're training their binoculars more and more on dragonflies. But I'm disheartened to hear that the Dragonfly Society of the Americas is inventing English-language "common" names for every species in North America, so that speakers of the other languages of the Americas won't know what we're talking about. Though I'm an old yankee myself, this seems like an unnecessary example of short-sighted yanquismo.
 
I hear fishkeepers floundering around, hampered rather than helped by using some of the fancy "uncommon" names that dealers coin in hopes of sparking sales. Sometimes a cagey marketing name will help sell an unsellable fish, like Gyrinocheilus aymonieri. Calling this fast-growing terrorizer a "Chinese Algae-eater" gives it a trade name that chimes vaguely with "Siamese Algae-eater" and makes you think you have the "right" fish— which you don't, in this case! One dear little "Pleco" mistaken for another will continue to surprise fishkeepers by attaining lengths of a foot or more. And the fancy names for gouramis multiply faster than the fish farms can manufacture the hybridized fishes themselves.
 
Besides the ersatz "uncommon" names of retailers, there are honest local names, though they tend to vary from area to area, and they can be applied to more than one kind of fish. Outside your home area, such names can make the other person's face go blank, just when you're trying to find out whether maybe you're both talking about the same fish. Since your "Blue Acara" may be Æquidens pulcher or Æ. caeruleopunctatus, which one is the "real" Blue Acara.
 
Common names may jump: the sobriquet "Jack Dempsey" is no longer applied to the species of fish it originally described. And if, like many fishkeepers younger than me, you don't know who the eponymous William Harrison 'Jack' Dempsey, the 'Manassas Mauler' was, what's the gain?
 
The rule: Unless there's a very familiar authentic common one, be fearless about using the scientific name. If it's a somewhat unfamiliar fish to you, or if you've discovered it just recently, all the more reason to use its real scientific name. If the scientific name's just "gobbledy-Greek" to you, then you could be missing something of value. So, for authoritative translations of Latin and Greek scientific names, go to ScotCat and click on "etymology." The emphasis is on names used for catfish, but you'll find that many specific names tend to get used over and over: variegatus keeps turning up, like Jennifer and Mark, in many families.
 
And I can't resist giving you this classic science nerd's link, Mark Isaaks' "Curiosities of biological nomenclature" periodically updated with new official zaniness. If you're not in the mood for biohumor, or a list of those pseudo-scientific names in the "Road Runner" cartoons, Isaaks' article "The Rules we play by" at the site soberly explains the universal rules of zoological nomenclature.