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Sustainable freshwater fishkeeping: Insights from aquarist Rachel O'Leary

Sustainable freshwater fishkeeping: Insights from aquarist Rachel O’Leary. There are nearly 33,000 species of fish in the world. Almost half of that number live in freshwater—an astounding level of diversity given that only around .01% of the liquid water on the Earth’s surface is fresh. Since the mid-19th century, the popularity of keeping them—and their saltwater cousins—in home aquariums has grown exponentially, with new and innovative techniques allowing for the husbandry of ever-more rare and particular specimens. 

Perhaps a billion fish are bought and sold each year, to the tune of up to $30 billion, with the majority going from some 125 countries to the United States, western Europe, Japan, and Australia. Of the more than 7,000 species that are available to hobbyists, some 5,300 are freshwater species. Around 1,000 freshwater species comprise the bulk of those kept in captivity. 

In press coverage of the various sustainability issues that affect the aquarium trade, freshwater species have gotten short shrift. This is understandable in some respects: around 90% of freshwater aquarium fish are bred in captivity. Concerns about their harvest in the wild pale in comparison to the issues facing saltwater fish. Around 90% of saltwater fish in the trade are wild caught, raising serious concerns about environmental impact. While wild harvest of saltwater fish may be sustainable for some more-common species, it can be devastating to smaller populations. And, if not done using proper technique, collection can have cascading effects throughout the reef ecosystems from which the most desired species are taken. 

The use of sodium cyanide to stun fish hiding in crevices to ease the capture process not only results in high mortality rates but also injures other organisms. Further, the removal of key species that feed on algae may allow blooms that smother delicate corals. The fish that survive capture using sodium cyanide frequently suffer long-term consequences and eventually perish as a result after they are purchased—thus creating a need for additional harvest. Even captive rearing of some species—such as the spectacular Bangaii cardinal fish (Pterapogon kauderni)—only creates further demand. 

Because captive breeding cannot keep pace with the desire by saltwater aquarists to own the fish, the slight increase in availability creates a feedback loop wherein more wild fish must be collected to satisfy the market. And most high-demand saltwater fish are difficult or impossible to breed anyway because they are pelagic spawners—their eggs are laid in open water and result in delicate larval forms whose needs are difficult to meet in captivity. Such is the case with the blue tang (Paracanthurus hepatus), brought to popular attention by Pixar’s Finding Nemo and Finding Dory films. It has been over-collected in the wild and is still much desired for display tanks.

While the issues raised by saltwater collection have captured most of the headlines, the freshwater fish industry has its own problems. Some fish are over-collected in the wild, others have been introduced to non-native waterways and have created problems there, and the collection of aquascaping materials raises further questions of sustainability. Proactive and knowledgeable fishkeepers are intent on mitigating these issues when they arise. 

To gain some further insight, I talked to YouTube star Rachel O’Leary, who documents her aquarium adventures to an audience of some 124K subscribers. She films and describes both her personal aquariums and her commercial activities, which include the sale of numerous varieties of fish and the design of aquariums for a wide variety of clientele. 

O’Leary often discusses how she sources her fish and materials in her videos and is thus an excellent resource for the novice aquarist attempting to develop a sustainable, ecologically friendly freshwater tank. On several levels, freshwater tanks do appear to be more sustainable than saltwater setups. The general maintenance of freshwater tanks demands less energy than saltwater reef tanks, which require additional electricity due to their need for powerheads to create currents that simulate the ocean environment and such complex equipment as protein skimmers.

Also, because freshwater fish are generally easier to breed, the demand for wild-collected animals is lower. Captive-bred specimens meet the requirements of the market in most cases. And in the context of freshwater fish harvesting as a whole, most of which goes to meet demands for food, the aquarium trade is a drop in the proverbial bucket. (Despite the more-damaging effects of the saltwater aquarium fish trade, the same is true of marine fisheries.) Still, the collection of fish does have an impact on the ecosystems in which the gorgeous creatures that adorn our living rooms evolved. So, how do we go about making sure that their wild relatives have a fighting chance?

Cardinal tetra, Image Credit: Brian Gratwicke/Flickr

According to O’Leary, one useful standard is ensuring that dealers are compliant with the code of conduct established by Ornamental Aquatic Trade Association, which provides detailed guidelines regarding the care and shipping of fish.

Further, she says, “If I see any protected (CITES or otherwise) species on a list, or on a list from a country neighboring where the fish originate, I also will not buy from them. L46 [Hypancistrus zebra, a species of plecostomus catfish] is a great example. They are from the Rio Negro, but you will see them on lists of other, nearby South American countries from time to time … This is evidence of at the very least illegal transportation with intent to sell … For the most part, it boils down to asking where and how fish are collected, and if answers are not readily provided, I avoid that source.“

This is complicated by the fact that some species are threatened in the wild by factors aside from collection. It may actually be beneficial to bring a small number of them into captivity in order to establish reserve populations. There has been intense debate over the zebra plecostomus, for example, which is threatened in its native Brazil by the development of hydroelectric dams. Would it be better to allow export, thus establishing populations in captivity, or to allow it to go extinct entirely due to human activity? Such fish as the now-ubiquitous white cloud mountain minnow (Tanichthys albonubes), and red-tailed black shark (Epalzeorhynchos bicolour), familiar to anyone who has perused the fish at big box pet stores, now exist largely in captivity, having been nearly extirpated in the wild due to environmental damage.

“There are many fish that I buy specifically because their natural habitat is so threatened by gold mining, palm oil production, farming, or industry,” O’Leary confides.

According to the IUCN, freshwater fish may be the most threatened group of vertebrates. Fishkeepers are encouraged to search for species that they are interested in on the IUCN’s site if they are unsure of their protection status.

Bringing rarer fish into the hobby can also aid in their preservation by raising awareness of their unique situations. The CARES Fish Preservation Program aims to facilitate this process by maintaining a list of priority species. “The vast majority of the fish, and invertebrates that I am interested in working with should be on the CARES list, yet get little attention as they are not “expensive” fish, nor as flashy … so often [they] don’t get the money or press for conservation,” says O’Leary.

“Captive breeding is incredibly important for many reasons,” she asserts. “…It important to sustain species [and] share them with other breeders. It helps further our knowledge of what husbandry, diet, and conditions these fish can thrive in, rather than just surviving. Captive programs for fish that are threatened in the wild are incredibly important, though there is a fine line between preserving a rare species because we need to, and profiting from the rarity.”

“I work with quite a few rare species, most specifically plecos from the Rio Negro,” she elaborates. “I do have a moral conflict about publicizing it, because creating a buzz around a species increases the demand, and increases the likelihood that it will be harvested unethically. I tend to do that work more quietly, and share information and species with other folks who are dedicated to sustaining species, rather than selling fish.”

Captive breeding has also served as a buffer for species that were initially over-collected due to their distinctive appearances. Now, sustainable captive populations more than satisfy the demand for such striking fish as the tiger barb (Puntius tetrazona), bala shark (Balantiocheilos melanopterus), and Boeseman’s rainbowfish (Melanotaenia

boesemani), all of which saw alarming declines in the wild after aquarists noticed their stunning coloration. More recently, in the early part of the 21st century, the wild population of the celestial pearl danio (Danio margaritatus) plummeted a scant year after its discovery—its constellation of silvery spots, augmented by red fins, were too much to resist. The efforts of hobbyists to establish captive populations have since alleviated those pressures. 

“There are many fish that do quite well just being farmed, and where it is unnecessary to collect the wild type,” O’Leary expounds. For example, wild populations of Betta splendens and angelfish (Pterophyllum scalare) have little to fear due to the proliferation of captive-bred varieties that far outshine the subtle appeal of their ancestors with their elaborate finnage and novel color combinations.

Boesemani rainbow fish, Image Credit: Leonardo DaSilva/Flickr

Captive breeding also goes some way in preventing mortality of fish, due both to more-controlled initial conditions and shorter shipping times with fewer stops along the way. Breeding facilities in developing countries may provide steadier and more remunerative work for people who might otherwise be engaged in wild collection. Most operations, however, exist outside of collection areas in such Asian countries as China, Indonesia, Japan, Thailand, and Malaysia as well as in Europe and Florida in the United States.

Despite these efforts, certain fish do remain at risk from overcollection. As novel species of rainbowfish (families Melanotaeniidae and Bedotiidae) are discovered, their populations come under increased collection pressures, which can be a problem when their numbers have not been accurately assessed. Collection practices for the clown loach (Chromobotia macracanthus), a popular species from Indonesia, were recently revised. Initial protections for this dynamic, striped bottom dweller did not take into account their breeding season and thus did not adequately shield mature fish from overharvesting. Now, more stringent size restrictions that allow for the capture of only smaller, immature fish will hopefully ensure that reproducing adults remain to replenish wild stocks. One study found that perhaps a third of the species exported from India were threatened or endangered. And in Africa, such cichlids as Pseudotropheus saulosi of Lake Malawi and Tropheus duboisi of Lake Tanganyika are endangered in the wild in part due to overcollection. “I do avoid buying fish from Lake Tanganyika that are wild caught,” says O’Leary, “as there are supposed to be anti-netting and anti-fishing laws in place, yet a few unethical folks are continuously importing fish from that region.”

Adding to the ethical complexity of wild collection is the fact that in select cases, even relatively intensive harvests may actually provide a net benefit to all entities involved, from locals who capture them to the ecosystems from which they are taken to the fish themselves. One example is the cardinal tetra (Paracheirodon axelrodi), a species native to the Orinoco and Rio Negro rivers in South America. This flashy little schooling fish has given rise to a thriving industry that provides some 80% of the income to a number of muncipalities along one section of the Rio Negro in the state of Amazonas in Brazil. Because many are harvested from seasonal pools that ultimately dry up anyway, killing the marooned fish, both the people who depend on them for a living and the fish themselves reap the rewards from North American demand for this lovely tetra. And it has been hypothesized that were the residents of the area not employed in scooping up their flagship species and selling it, they might be logging and ranching instead—far more damaging to the imperiled rainforest. Project Piaba, named for the Portugese word for aquarium fish, aims to raise awareness of the benefits of this sustainable industry and others like it in the Amazon.

“Wild collection can go quite a long way to support local people who otherwise would seek employment in more ecologically destructive ways of life,” explains O’Leary. “It CAN be done well, especially if the importer, wholesaler, or end consumer is willing to pay a fair market value for the species collected. This is a big issue, IMO, in the United States.”

Then, of course, there is the issue of unwanted fish. Though in temperate climates, it is less of an issue because most tropical fish that are dumped cannot survive colder fall and winter temperatures, in more tropical areas, notably the South of the United States, invasive species can become a problem. Plecostomus have invaded waterways in Texas, Florida, Mexico, and Sri Lanka after being dumped by aquarists or escaping from fish farms. These catfish have disrupted ecosystems and outcompeted native fish as well as introduced disease. Dumping is a particular problem for fish such as pacus, which are purchased as manageable juveniles but grow to massive sizes in relatively short order. Because they rapidly outgrow the average home aquarium, many specimens are released by well-intentioned owners. They have been found in lakes and rivers in regions ranging from the United States to remote Papua New Guinea. Though their impacts are poorly studied, their enormous proportions make it likely that they may present stiff competition for less robust natives. Fishkeepers would do well to research the adult sizes of fish they are interested in keeping so that they can ascertain whether or not they are capable of sustaining them throughout their lifespans.

Even the materials that aquarium hobbyists use to decorate their tanks can have environmental implications. While most plants used to create the naturalistic aquascapes popularized by Japanese aquarist Takashi Amano have been successfully cultivated, some of the materials such as wood may be an under-investigated area of impact. The harvest of the twisted branches of the manzanita shrub, commonly used to provide visual structure and perching places for aquatic organisms, may actually have a positive effect. Sustainable freshwater fishkeeping: Insights from aquarist Rachel O’Leary

“I do buy my manzanita from a man who has a permit for collection, which is actually really important to help prevent some of the devastating forest fires we have seen in California in recent years,” says O’Leary.

Such are the complexities of aquarium keeping—even the unexpected can result in consequences (and, occasionally, benefits) for the external environment. In creating tiny ecosystems in our living rooms, we must consider all of the components, from the fish to the water to the energy required to filter and light them. An increasing level of awareness among those who care about their inhabitants, and the efforts of experienced fishkeepers like O’Leary, has made keeping aquariums in a sustainable manner easier than ever before.

By Richard Pallardy, Contributing Writer

Image Credit: Marco Verch/Flickr

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