New hobbyists are often dismayed to find that many of the organisms offered for sale in our interest are poorly suited to captive conditions. In fact; there are several that are not known to have eaten aquarium foods. . . ever. Other species get too large, are too mean, aren’t even tropical!!!
So why are these errant fishes (and more) actually proffered at fish stores? The simplest answer is “because they sell”; but as usual, there is a more involved, total answer. There’s a “founder” (or flounder) effect that is a type of social inertia in the trade, where fishes that have been caught for decades just continue to be captured, sold through the chain of custody: collector, wholesaler, perhaps jobber, transhipper, retailer and etailers, to the end user, you and I, the aquarist. To some extent, these animals are more common/numerous, easier to catch, and may well ship well and live for a while.
Here I’ll make up some general categories, elaborate on what they mean, and cite some species in each that show up very regularly for sale in the trade.
Bad Species: Poor Capture, Transport, or Adaptability Record:
One outright contraindicated behavior to avoid in livestock selection is death itself; some species, for whatever unknown reasons, don’t generally live through the rigors of collection, holding and shipping. This list of “poor survival fishes” is quite long. Some too-often seen:
Size Matters: Both Too Big and Too Small:
There is an optimal range of better to best sizes for each species of fish. Too little ones can’t take the rigors of capture, non-feeding. Too large ones also ship poorly, rubbing themselves raw often, and adapt poorly to captive conditions. In-between is the “sweet spot” for each.
Does the Species Eat Captive Foods?
Know that a species historical feeding record has little to do with the fact that it is being offered in the trade. There are organisms that have scarcely known to have eaten anything in captivity. Some examples are coral and other specialized-feeding Butterflyfishes (Chaetodon reticulatus, Webbed Butterflyfish; Chaetodon ornatissimus, the Ornate; and the Exquisite, Chaetodon austriacus among many others). Beware of these and other “miscellaneous” Butterflyfishes. Other species include the Pinnatus Batfish, Platax pinnatus (now aquacultured and a bit hardier for it) and Moorish idols, Zanclus canescens. More than 95% of these die within a month of wild-collection. These two fishes rarely take food in captivity; most dying mysteriously.
There is a surprisingly large number of venomous, otherwise toxic fish species in the world; some are sold as pets.
Most boxfishes and trunkfishes (Family Ostraciidae) (Cowfish, Lactoria cornuta, right) and Soapfishes can release toxic materials into the water should they “become upset.” One must choose tankmates carefully with these fishes. Other fishes have venom and the means to inject it: Including Plotosid catfishes (Plotosus lineatus),
Of course you are aware that Scorpionfishes and their kin are venomous. I still endorse the sale of Scorpaenids such as lionfish and stonefish but one should always have their eyes open when arms, hands are in their tanks.
Too Big Boys (and Girls):
Some fishes sold as juveniles are oh-so cute! But, a few of them are real tank busters.
A fave example is the Clown Coris Wrasse. So delightful when small. But should yours live, it might grow into a two foot long female and then become a three foot male! Oh boy!
A woeful mention of coldwater life placed in tropical aquarium waters. Yes; there are non-warm water species sold in the trade that won’t live at high temperature.
Catalina Gobies ( Lythrypnus dalli), Leopard Sharks ( Triakis semifasciatus) as well as cool/coldwater snails, algae, anemones are all coldwater species. Let the buyer beware!
So are the folks in the pet fish industry a bunch of charlatans; heartlessly selling livestock that they know full-well is not likely to fare in our captive systems? I think not. Many are simply ignorant of how touchy some of the life they sell is; passing on what seems to be hearty specimens to willing consumers. The better stores and etailers DO their best to inform would-be purchasers of issues they may well face with given species, geographical varieties, and size ranges of marine fishes. Quite a few shops eschew carrying “doomed species” period.
As consumers, it is up to each of us to arm ourselves with knowledge, and either avoid these poor choices, or at least be aware of their inherent challenge. It is ultimately up to you to cast your votes with your money in buying or leaving what you consider of value and not. Do be aware that your actions in turn strongly influence what will go on to be caught and cultured. Choose well.