Читать книгу Angelfish - David A. Lass - Страница 8

CHAPTER 1

Where in the World?

Chances are you will never see a wild angelfish in your local fish store. Virtually all the angelfish available to the hobby today are produced commercially on a more or less massive scale, from the basements or garages of local hobbyists everywhere to large fish farms in Florida or the Far East. Even though it is very unlikely that you will ever encounter a wild angelfish, we can learn much about these fish in general by looking at where they came from originally and how they live in the wild.

These wild angelfish are of the variety often called the Peruvian altum. This variety is rare and is not often seen in fish stores.

ANGELFISH IN THE WILD

There are three species of angelfish—Pterophyllum altum, P. leopoldi, and P. scalare—all of which originated in the Amazon River basin in South America, primarily in Brazil but also in Peru and Colombia. The main branch of the mighty Amazon River is formed around Manaus, Brazil, a port city where the Rio Negro and the Rio Solimões merge in the famous “wedding of the waters” (also known as the “meeting of the waters,” or, in Portuguese, Encontro das Águas). The warmer, slower waters of the Rio Negro, which flow from the north, are almost black, full of dissolved vegetation and other organic material. The colder, faster waters of the Solimões are almost yellow, full of silt and other mineral particles washed into the river from its many tributaries in the Andes. From Manaus to a point many miles downstream, they seem to run separately in the same bank, the northern side of the Amazon black and the southern side yellow, until the waters finally mix to the muddy brown color the river keeps all the way to the Atlantic.

My introduction to the Amazon started with an eight-hour flight that was truly amazing. For hour after hour we flew over the jungle, a green carpet broken only by a river or a lake here and there. Once in a while we could spot a wisp of smoke from a native settlement, the only sign of human presence. A few hours into the flight, we passengers were freely wandering the plane. By the time we neared Manaus, I was talking with the two crew members and enjoying the view from the cockpit jumpseat. The pilot started making wide, arcing S-turns. I asked him what he was doing and he replied, “I’m looking for the river.” I asked for some explanation, and he said that it was hard to navigate over the endless green of the jungle and their instruments were not all that accurate, so he normally located Manaus by looking for either the Rio Negro or the Solimões. That day he spotted the Rio Negro, and we followed it to Manaus, getting an incredible view of the wedding of the waters from about 2,000 feet.

Transporting people and cargo along the Amazon, a boat makes its way along the “wedding of the waters” (also called the “meeting of the waters”) in the vicinity of Manaus, Brazil.

Angelfish are found throughout the tributaries of the Amazon, primarily in the small creeks and almost still pools and small lakes that feed the Rio Negro and the Solimões. This natural range is generally referred to as the flooded forest, but the term accurately describes local conditions only during the rainy season, roughly December through May. The dry season (or not-so-rainy season) includes the other six months of the year. While average temperatures in the tropics vary little from one season to the other, the water levels in the region change dramatically. When the rains flood the forest, water levels rise as much as 50 feet above dry-season levels.

THE “WEDDING DRINK”

My friend Scott Dowd, the senior freshwater aquarist at the New England Aquarium in Boston, leads an expedition at least once a year to the Amazon basin, concentrating on the area between Manaus and Barcelos in Brazil. To celebrate the “wedding of the waters,” Scott creates a special drink by filling a beer stein halfway with Antarctica Pilsner, the most popular light beer in Brazil. Scott then pours in Guinness Stout (which he has hand-carried from Boston) over an inverted spoon, so the dark stout floats on top of the lighter pilsner. When you drink the beer, the two slowly mix together, just like the wedding of the waters. Scott points out that this is done on all of his Amazon trips when they first see the actual wedding of the waters, regardless of the time of day or night.

THE AMAZON RAIN FOREST

This area is an amazing rain forest—for the most part, pure unspoiled jungle. I saw it for the first time in the early 1970s from a DC-3 cargo plane en route to Manaus from Panama. We—my two traveling companions, two other passengers, and I—boarded in Panama at five o’clock in the morning. The cabin held two banks of three seats precariously bolted to the floor, and boxes of cargo filled the rest of the space. As we prepared to depart, one of the pilots told us that because the plane carried passengers it was bound by all of the rules for passenger airlines, which meant that we must keep our seat belts fastened at all times. He then tied the door shut with a length of clothesline rope, and we were off.

Aerial view of the Rio Tapajós, which meets the Amazon River in Brazil

What this means for angelfish is that, during the rainy season, the water is freshened and there is plenty of food around. Angelfish, along with most of the other fish in this great body of water, spawn frequently, producing many thousands—actually, make that millions—of baby fish trying to survive but mostly providing food for the larger species. Fruits and insects are also abundant during the rainy season—it is a time of easy and bountiful feeding for the fish. In addition, because the volume of water increases significantly, the adult fish are less likely to fall prey to other fish, as they have so much more room to swim and more places to hide.

At the time of high water along the Amazon, the water literally invades the land, creating flooded forest areas such as this one, near the Rio Nhamunda in Brazil.

When the dry season comes and the waters recede, conditions in the Amazon basin become less friendly. As the volume of water decreases, the fish population becomes more concentrated, and competition for hiding places and food increases. The baby fish that have survived the rainy-season spawning need more food as they mature, but there is much less in the way of fruits and insects to feed on, so the fish go for long periods of time without much food—as well as prey more on each other. This eat-or-be-eaten situation makes the outlook fairly bleak for an angelfish in the dry season. Fortunately, the rains eventually come again, life in the river improves, and the cycle continues.

HABITAT IN THE WILD

As noted, angelfish exist in the wild through much of northern South America, primarily in the huge expanse of jungle from which the Amazon River and its tributaries drain into the ocean. This vast basin encompasses much of Brazil, Peru, and Colombia, and altum angels and altum/scalare hybrids are found as well in the upper Rio Negro and Rio Orinoco basins in Guyana and Venezuela.

This is the Rio Nhamunda (same GPS location as the photo on the previous page) during the dry season, when the lower water levels force angelfish to compete for precious food and hiding places.

THE RAINY SEASON

According to my good friend Arie DeZwart, a co-owner of Ruinemans Aquarium (Montfoort, Holland; Miami, Florida; and Manaus, Brazil) who has been involved with South American fish for many years, the timing of the beginning and end of the rainy season is less reliable and less predictable than it has been in the past. Arie also observes that at some times and places it simply doesn’t rain enough to cause the waters to rise and flood as they must. He points out, however, that while global warming may be a factor in these trends, similar situations are known to have occurred fifty years ago.

Water Conditions in the Wild

The typical angelfish habitat in the wild is not the sparkling clear water of either the local fish store or your home fish tank. The waters of their natural habitat range from cloudy to black, waters so dark you can barely see your hand in front of your face. Also unlike most aquariums, many of the places angelfish come from in the wild do not have any plants, with the exception of the shallows at the edges of rivers and ponds. The water is much too dark, and often much too acidic, for most plants to grow. Typical angelfish habitat consists of a profusion of submerged tree limbs, branches, and roots—the result of years and years of jungle trees’ growing and falling into the water and shifting and swirling as the waters rise dramatically in the rainy season and fall in the dry time. It is within this maze of pieces of wood that angelfish are usually found. The conditions in the flooded forest change dramatically over the course of the year, and wild angelfish are well adapted to the wide range of pH and hardness that changing water levels entails. Similarly, the vast majority of angelfish that are now commercially raised have become well adapted to the water conditions of the fish farms, your local fish store, and your aquarium.

The Rio Momon in Peru, shown here, is a typical angelfish habitat, with dense plant growth, scattered driftwood, and fallen tree trunks for angelfish to hide among.

Light filters down through a maze of driftwood, tree roots, and dead branches in the Rio Xingu tributary in Brazil, creating the perfect natural habitat for angelfish.

The water conditions where P. scalare are found in the wild are generally soft and acidic and allow for some variability—pH of around 6.5 and hardness of 4 to 5, and a temperature of 75 to 80 degrees Fahrenheit. Variations in both pH and hardness are small at a single location but can be significant from one place to another. The situation is very different with altum angels. These are found only in locations with a pH of 5.0 or lower, virtually no hardness, and temperatures ranging from 80 to 85 degrees Fahrenheit. Fortunately, all of the angelfish you will see in local fish stores adapt very well to any conditions around neutral pH and moderate hardness, since all of the fish you will see in the hobby have been commercially raised under those conditions.

Diet

In the wild, angelfish are pretty much the top of the piscine food web, in that the only fish that would eat an adult angel would be a red-tailed catfish or another of the larger catfish. Baby and subadult angelfish, however, are prey to larger fish throughout their habitat, and angelfish of all sizes are fair game to other animals, such as caiman and other fish-eating creatures avian, mammalian, and reptilian. In the wild, angelfish are omnivores, eating anything that they can. Their diet varies by the season and by what is available. Their wild diet would normally consist of a variety of crustaceans and insects and their larvae, as well as any small fish they can catch; angelfish will also eat fruit and other forms of vegetation if that is all that is available.

Large shovel-nosed catfish such as these are found in the wild along with angelfish. These catfish will prey on angelfish of all sizes, along with anything else they can catch and swallow.

Shoals, Not Schools

Angelfish occur in large groups called shoals, not in schools. The two terms describe very different kinds of behavior. Schools are usually considered to be many fish that move almost as one; they all swim in the same direction, turning and darting as a single entity. Shoals consist of many fish that basically are hanging out together but not necessarily pointing in the same direction and definitely not all moving in the same direction. Shoals of fish generally muddle around together, and the entire group gradually flows from one place to another instead of moving as a unified mass. To illustrate the difference between a shoal and a school, I think of my 300-gallon display tank, which contains seven large altum angels and around 150 rummy nose tetras (Hemigrammus bleheri). Eight large wild discus and many catfish and algae eaters also live in this tank. The angelfish are in a shoal, usually spread out within roughly a third of the tank, either looking for food individually or sparring with each other or some other fish. The school of rummy noses, in contrast, is always on the move, often in a line, its members streaming as one from one end of the tank to the other.

A fine shoal of young angelfish shows a number of the different color varieties that are available.

ANGELFISH IN YOUR TANK

Because I wholesale fish to local fish stores in the greater Boston area, I frequently chat with hobbyists and store owners about angelfish. I am always amazed that very few of them—not even the store owners—have any idea where angelfish come from. Store owners usually tell me, “Angelfish come from you—you deliver them to my store,” and hobbyists almost always say, “I dunno—I get them here at Joe’s Pet Place—that’s where they come from.”

From the farms where they are raised on the other side of the world, the fish are brought to a local central broker or holding facility where they are prepared for shipping. Fish are shipped by air freight in cardboard boxes roughly three feet long by two feet wide and a foot and a half in height. Inside the cardboard box is a Styrofoam box to keep the fish at a steady temperature, and inside the Styrofoam box is a heavy-duty plastic bag. The bag is one-third filled with shipping water and angelfish—a typical bag holds between 150 and 200 small (dime to nickel body size) fish—and then inflated with pure oxygen. Heat packs may be added in the winter to keep the fish from freezing in transit; ice packs may be needed in the summer to prevent them from overheating. Shipments consisting of many boxes of fish are then air freighted to the United States to importers and distributors in the primary ports of entry, New York and Los Angeles. From the importer, the fish go on to local wholesalers, who sell fish to the local fish stores, who sell them to you, the hobbyist.

FISH FROM ALL OVER THE WORLD

Most of the angels in the hobby today come from Florida and the Far East, meaning Singapore, Indonesia, Sri Lanka, Thailand, and China. Unlike in Florida, which is dominated by large fish farms, fish cultivation in the Far East is a cottage industry, with families specializing in one or two species. I visited the section of Singapore where fish farming is centered; there, the man in one house specializes in, say, albino Corydoras, his next-door neighbor raises fancy swordtails, and the next guy Mickey Mouse platies.

Angelfish are shipped from the Far East or Florida to wholesalers in plastic bags filled with water and oxygen; the bags are placed inside a Styrofoam box, which is then placed inside a cardboard box.

The time interval between netting an angelfish from a holding tank at the fish farm and putting it in your tank at home can be as short as a few days or as long as a week or more. Shipping fish across such great distances puts them under incredible stress. The pH of the water in the shipping bags is often dangerously low, and the level of ammonia and nitrites very high. Many improvements have been made in shipping practices, primarily those by the Singapore fish breeders but also those by the Florida Tropical Fish Farms Association (FTFFA). Inevitably, some fish do not survive shipment, but considering the tremendous volume of fish shipped all around the world every week, the actual losses are negligible. When you realize how far the fish you buy in your local fish store have traveled—halfway around the world or farther—you can appreciate how hardy tropical fish in general, and angelfish in particular, must be.

HABITAT DESTRUCTION

Even though their angelfish most likely come from commercial farms rather than from the wild, folks who keep tropical fish—and who usually care about animals and the natural world—should be aware that the natural environment of angelfish is under tremendous destructive pressures. The Amazon rain forest is the largest pristine jungle and rain forest in the world—sometimes called the lungs of the planet because the huge amount of plant biomass it contains absorbs so much carbon dioxide and gives off so much oxygen. This vital resource for all the inhabitants of the earth is being systemically destroyed on a major, and constant, scale. Economic interests such as logging, mining, and farming are cutting down the trees of the rain forest by clear cutting, destroying ecosystems by mining for minerals, and then dumping chemicals on what is left of the land so people can grow forage crops and raise cattle.

A group of angelfish spend some time at a holding station in Manacapuru, Brazil. These fish display unusual patterns of stripes on their bodies, typical of recently caught angelfish acclimating to an aquarium environment.

A fisherman does his job along the Amazon, amid the typical tangle of fallen trees, branches, and driftwood, where angelfish are found.

Many groups are actively trying to preserve and protect the Amazon rain forest. One that is integrally bound with the tropical fish hobby is Project Piaba. Piaba is the generic name the indigenous inhabitants of the Amazon River basin give to any small fish, especially the less colorful species that swim with the cardinal tetra (Paracheirodon axelrodi). The motto of Project Piaba is “Buy a Fish, Save a Tree,” and the mission of the organization is to support the local fishermen and their families who make their living collecting ornamental aquarium fish, the most important one of which is the cardinal tetra. In a somewhat counterintuitive manner, Piaba wants hobbyists to buy fish that have been responsibly collected in an “eco-friendly” way from the Amazon by these fishermen.

DESTRUCTION OF RAIN FORESTS

The Amazon rain forest is one of the last untouched pristine jungles left in the world, and humankind is doing its best to try to destroy it. Logging, mining, and farming interests destroy huge tracts of rain forest daily, in the name of “progress.” Project Piaba and other organizations are working hard to preserve the rain forest; please support these efforts.

Project Piaba had its origins in studies on the fishing industry around the town of Barcelos on the Rio Negro, conducted by ichthyology professor Ning Labbish Chao in the late 1980s. Barcelos is the center for the collection of the cardinal tetra, which are collected by the millions and shipped by boat from Barcelos down to Manaus at the confluence of the Rio Negro and the Solimões. Dr. Chao has begun to organize the local fishermen in Barcelos, and he has established a system of permits for the collection of ornamental fish. That was the first step toward making sure that the products of the Amazon rain forest, a large share of which are ornamental tropical fish, are harvested on a sustainable basis and ultimately that the rain forest is preserved. If the fishermen can make their living by selling the ornamental fish, which are essentially a renewable rain forest resource, they will protect their fishing grounds from destruction by the loggers, miners, and farmers. Local fish stores in the United States are beginning to offer eco-friendly fish from sources approved by Project Piaba. When you see fish in your local fish store that are labeled as being wild caught from the Amazon—cardinal tetras, rummy noses, hatchet fish, Otocinclus, and bleeding hearts, to name a few—you can feel good about buying them and doing your part to protect the Amazon rain forest.

Dr. Ning Labbish Chao spends time out in the field, working with the fish.

Scott Dowd, of Project Piaba and the New England Aquarium, and I ran a test project involving some of the local fish stores to which I wholesale fish. We wanted to know if retail customers of the fish stores would prefer cardinal tetras that were taken from the wild in an environmentally responsible manner, as with Project Piaba, over commercially farmed cardinal tetras. Unfortunately, we had trouble keeping the commercially farmed cardinals alive, which we presume is only a temporary problem, one that will be solved eventually as it has been with most other ornamental tropical fish. Even though we didn’t have a full opportunity to test the actual choice, we were very pleased to see from our surveys that the vast majority of the customers, once they understood why it is better to purchase wild cardinals—because the fishermen protect the rain forest—preferred the wild-caught cardinal tetras. Many of the respondents said that they would even be willing to pay a premium for the wild-caught fish, knowing that by doing so they would be helping preserve the Amazon rain forest.

Wild-caught cardinal tetras swim in a home aquarium. These fish are a good choice for the hobbyist interested in helping preserve the Amazon rain forest.