Fish in Tanks? No, Thanks!

Fragile tropical fish, who were born to dwell in the majestic seas and forage among brilliantly colored coral reefs, suffer miserably when they are forced to spend their lives in glass tanks. The same is true of river fish. Robbed of their natural habitats and denied the ability to travel freely, they must swim around endlessly in the same few cubic inches of water.

Where Fish Really Come From
The popularity of keeping tropical fish has created a virtually unregulated industry that catches and breeds as many fish as possible, with little regard for the animals themselves. While many species of coral are protected under the Convention on International Trade in Endangered Species of Wild Fauna and Flora, most fish who end up in aquariums are not.1

Because most saltwater fish cannot be bred in captivity, up to 98% of those sold in pet stores come from the wild, mostly from the waters around Southeast Asia, Fiji, and Hawaii.2 More than 30 million fish, along with millions of other types of marine life—such as anemones, shrimp, and mollusks—are captured every year to support a $200 million worldwide “hobby.”3,4 Some species, such as the Banggai cardinalfish, have become threatened because of fishing.5

According to a 2008 report from the National Oceanic and Atmospheric Administration, up to 90% of saltwater fish brought to the U.S. for display are caught illegally using poison.6 Collectors douse coral reefs with cyanide, which is ingested by the fish who live there, and as reported in Scientific American, “The resulting asphyxiation stuns some fish and sends others into spasms, making them easy to grab by hand or net.”7 Studies have shown that as many as 75% of fish poisoned with cyanide die within hours of collection and that another 30% die before they’re ever shipped.8 The cyanide also kills coral and millions of other fish, invertebrates, and microscopic animals.9 Marine biologists rank the poison as one of the biggest dangers in Southeast Asian waters.10

Approximately 90 percent of freshwater fish are raised on farms.11 Goldfish, for instance, are usually bred in giant tubs in facilities that produce as many as 200 million fish per year.12 These animals are sold to zoos, pet stores, and bait shops, and many are doomed to live in plastic bags or bowls, neither of which provides the space or oxygen that goldfish need. The city of Monza, Italy, banned keeping goldfish in bowls because the containers do not meet the needs of the animals and because, as one sponsor of the law pointed out, bowls give fish “a distorted view of reality…and (they) suffer because of this.”13

Fish Can Speak, Make Tools, and Think
Fish have cognitive abilities that equal and sometimes surpass those of nonhuman primates. They can recognize individuals, use tools, and maintain complex social relationships.14 Biologists wrote in Fish and Fisheries that fish are “steeped in social intelligence, pursuing Machiavellian strategies of manipulation, punishment and reconciliation, exhibiting stable cultural traditions, and co-operating to inspect predators and catch food.”15

Fish communicate with one another through a range of low-frequency sounds—from buzzes and clicks to yelps and sobs. These sounds, which are audible to humans only with the use of special instruments, communicate emotional states such as alarm or delight and help with courtship.16 The pumps and filters necessary in many home aquariums can interfere with this communication. “[A]t the least, we’re disrupting their communication; at worst, we’re driving them bonkers,” says ichthyologist Phillip Lobel.17

What You Can Do
Please don’t support the tropical fish trade by purchasing fish. If you enjoy watching fish, consider downloading one of the many colorful and realistic fish-themed computer screensavers available on the web. Don’t support businesses or fairs that give fish away in contests or promotions.

Siamese fighting fish, who are often sold as “decorations” or party favors, are fighting for their lives as their popularity grows. Pet shops, discount superstores, florists, and even online catalogs sell Siamese fighting fish (Betta splendens) in tiny cups or flower vases to consumers who are often uneducated about proper betta care. These tiny containers are not suitable for any fish.

Biologists say that there is no safe way to return captive fish to their natural environments—which are often located in a completely different region of the world—because of the difficulty in locating such a habitat and the possibility of introducing disease to the other fish there. Researchers have found many species of non-native fish, including predatory species, living off the coast of Florida, and they attribute these populations to careless aquarium owners.18 These fish pose a real threat to native species. Never flush fish down the toilet in the hope of “freeing” them, as seen in popular movies like Finding Nemo. Even if a fish survived the shock of being put into the swirling fresh water, he or she would die a painful death in the plumbing system or at the water treatment plant.19

If you already have fish, you can make their lives easier by providing them with an environment that is as much like their natural habitat as possible. While captive fish can never live natural lives, the following tips will help ensure that they are as happy as possible:

• The more space that fish have, the happier and healthier they will be. Their needs vary, so check with an expert or consult a good fish book to determine their requirements. One general guideline is that you should provide 3 gallons of water for every 1 inch of fish.20
• Treat tap water properly before putting it into the aquarium, as most municipal water contains chlorine, which can kill fish. The type of chemicals that you should use depends on your area’s water. Consult with a local tropical fish supply store to determine the proper treatment.
• Different types of fish require different pH levels. Check the pH level daily for the first month and weekly thereafter.
• A filter to remove waste particles and noxious chemicals from the water is essential. Live plants help with this task and provide oxygen, shelter, hiding places, and the occasional snack.
• A properly working air pump is necessary to provide oxygen.
• Fish need a constant temperature and you should check with a fish supply store for information that is specific to the type of fish that you are keeping.21 Automatic aquarium heaters monitor the water temperature and turn the heater on and off as needed. Attaching a small thermometer to the tank will help you ensure that the heater is functioning properly.
• The natural waste of fish emits ammonia, which can accumulate to toxic levels, so clean the tank regularly, but never empty the tank completely. Be sure to clean the glass well with a pad or a brush to prevent algae growth.
• Create places for the fish to hide and explore. Ceramic objects, natural rocks, and plants work well. Make sure that all objects are thoroughly cleaned and disinfected before they are put into the tank. Do not use metal objects, as they will rust.
• Be aware of the environment outside the aquarium. Suddenly switching on a bright light in a dark room can startle fish, and vibrations from a television or a stereo can alarm and stress them.
• Keep all harmful chemicals away from the aquarium. Cigarette smoke, paint fumes, and aerosol sprays can be toxic if they are absorbed into the water.
• The aquarium should be in a spot where temperature and light are constant and controllable. Tropical fish supply stores may be able to advise you on the best amount of light for the fish you are keeping. Remember that direct sunlight and drafts from nearby doors or windows can change the water temperature, and fumes from a nearby kitchen or workshop can injure the fish.
• Don’t overfeed! Uneaten food and waste material are broken down into ammonia and nitrites, which are toxic. One expert recommends providing only as much food as your fish can eat in 30 seconds.22
• If a fish seems sick or lethargic, take him or her to a vet. Fish can be medicated, anesthetized, given shots, and operated on, just like other animals. Take along a separate sample of the tank water.
• Most fish enjoy companionship. If you have a single fish, check with friends and neighbors to find another loner to adopt—but don’t support the fish trade by going to a dealer.
• Supply stores and catalogs have clear plastic dividers available that can be used to create a safe section in a large tank for a betta fish who is living in a “community” aquarium. Make sure that the divider fits securely in the tank and provides necessary access to the surface.

1Sarah Simpson, “Fishy Business,” Scientific American 285 (2001): 82–90.
2Rachael Bale, “The Horrific Way Fish Are Caught for Your Aquarium—With Cyanide,” National Geographic, 10 Mar. 2016.
3Alastair Bland, “Ending the Ecologically Harmful Capture of Tropical Fish,” Pacific Standard, 9 Jan. 2018.
5National Oceanic and Atmospheric Administration, “Banggai Cardinalfish,” Species Directory, accessed 3 Feb. 2019.
6Andrew W. Bruckner and Glynnis G. Roberts (editors), “Proceedings of the International Cyanide Detection Testing Workshop,” NOAA Technical Memorandum NMFS-OPR-40, Aug. 2008.
8Bruckner and Roberts.
11Ashley Marranzino, “Where Do Aquarium Fish Come From?Massive Science, 16 July 2018.
12Joe David Rice, “World’s Largest Goldfish Hatchery Is in Arkansas,”, 19 Nov. 2018.
13Agence France-Presse, “Council Bans Goldfish Bowls,” 23 July 2004.
14Culum Brown, “Not Just a Pretty Face,” New Scientist, 12 June 2004.
15BBC News, “Scientists Highlight Fish ‘Intelligence’,” 31 Aug. 2003.
16Stephen Budiansky, “What Animals Say to Each Other,” U.S. News & World Report, 5 June 1995.
18Amitabh Avasthi, “Releasing Nemo a Disaster for Native Fish,” New Scientist, 2 July 2004.
19Kathleen Flynn and Allison T. Hoffman, “Fish Flushers Learn Life Does Not Imitate ‘Nemo’,” Los Angeles Times, 26 June 2003.
20Petset, “Goldfish Bowl Do’s and Don’ts,” The Washington Post, 8 Aug. 2004.
21Temperature Control,” Tropical Fish Magazine, accessed 3 Feb. 2019.
22Nathan Hill, “Don’t Make These Fishkeeping Mistakes!,Practical Fishkeeping, 17 Jan. 2017.

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