From the Editor
What Is a Fish?
Some people argue that since jellyfish aren’t fish, we should call them “jellies.” Despite the use of that term to refer to squishy plastic shoes, it works fine for jellyfish, but what is the problem with “jellyfish”? Nothing. In fact, even the basic argument—that these animals aren’t fish—is
extremely difficult to substantiate. Logically, the first thing would be to explain what
a fish is. You might want to say that fish have scales and fins, but reptiles and birds
also have scales, and dolphins and some octopuses have fins. Some extinct reptiles
had scales and fins.
Robert C. Boruchowitz
Sharks, which have scales and fins and are fish by most people’s reckoning, are
not all that closely related to most of our aquarium specimens, and, in fact, modern
biologists no longer use the “class Pisces” grouping that once collected fish in one
group. Instead, lungfish and all terrestrial vertebrates are in one group, animals
like cichlids and damselfish are in another, and sharks and rays are in a third. By
consensus, lungfish and damsels and sharks are called fish, but there is no biological
grouping (clade) that includes all fish and only fish, so “fish” is not a precisely definable term.
What about a non-technical definition of fish? Well, aside from all the finned, scaled vertebrates called fish, there
are plenty of scaleless fish, like catfish. Then, in addition to the motile cnidarians we call jellyfish, we call a lot
of other things “fish”: invertebrates like silverfish (insects), starfish (echinoderms), and shellfish (crustaceans and
mollusks); certain human beings like an easy mark for a swindler, a weak poker or chess player, or a member of
various professional sports teams with fishy names (including, interestingly enough, the Miami Dolphins, though
dolphins are mammals!); and even objects like a surfboard, a card game, and a torpedo. You see, language use
doesn’t have to be literal. Nobody is confused by these usages. In fact, they enrich our language.
The same people who want us to use only “jellies” want us to call starfish “sea stars,” but then should we
also talk about “closet silvers” for the bugs and “sea shells” for crabs and clams? Are we supposed to stop
talking about sawhorses and seahorses (which are fish!) because they aren’t equines? What about Welsh
rabbit, which is neither?
The point here is that unlike scientific names, most words are not technical terms, with precise definitions of the
things to which they can refer. Normal language use is adaptive, expressive, and poetic. People can easily handle
the logical inconsistencies because language isn’t about precise definitions, it’s about communication of ideas. In
the absence of a biological definition of “fish,” there is no logical motive for trying to change centuries of English
language use in a hypercorrect attempt to display the knowledge that jellyfish are invertebrates. There are so many
misunderstandings worthy of our efforts to counteract; why waste time on a nonissue like this? Nobody is confused
by their name and concludes that jellyfish are fish like goldfish or cichlids.
While English-speaking people in Taiwan are not confused by the name, they and their neighbors understand
that some jellyfish make great aquarium specimens, and we have an article this month that discusses keeping
jellyfish as pets, a fad that is currently taking Taiwan by storm (p. 92). The enormous variety of things described
by the word “fish” mirrors an enormous variety of things that interest aquarium hobbyists, and the rest of our
lineup reflects this broad range of topics, from a look at cichlid love (p. 32) to the—here’s another creative
name—toadstool corals (p. 52); from the aquarium care of a fascinating primitive fish called a “butterfly” (p.
68) to a colorful fish called a “devil” (p. 48); from a review of a huge Pennsylvania aquarium retailer (p. 106) to
creating a successful Caribbean biotope display at home (p. 98); from our monthly Nature Aquarium feature on
high-tech botanical aquascapes (p. 62) to a how-to article on low-tech, all-natural planted tanks (p. 80); and from
an even-handed consideration of both sides of the hybrid fish debate (p. 74) to a mathematical investigation of
that aquarium basic—water changes (p. 86).
Phew! And that’s not all, but I’m out of space. Read through the issue and see how the aquarium hobby is
as diverse and intriguing as the English language’s creative use of the word “fish,” and how each month we
capture it all!
Tropical Fish Hobbyist