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The hidden environmental impacts of tropical fish aquariums

In a recent study, experts at Cardiff University’s Water Research Institute quantified the carbon footprint and environmental impact of pet fish. The study revealed that tropical fish aquariums contribute to a significant proportion of annual household CO2 emissions and water usage.

There are approximately four million households in the UK alone with pet fish. Of these, it is estimated that a staggering 70 percent maintain tropical freshwater aquariums, according to Dr. William Perry, a research associate at the Institute.

Carbon footprint of pet fish

Traditionally, environmental studies have focused on the ecological footprint of domestic mammals, such as cats and dogs. However, this latest research shifts the spotlight to the previously overlooked tropical fish pet industry. 

“The carbon footprint of owning pets such as dogs and cats has been previously calculated, but we have provided the first estimates of carbon dioxide emissions produced from running a tropical aquarium, as well as estimated water consumption,” Dr. Perry explained.

Dr. Perry’s groundbreaking research examined the environmental implications of fish keeping in several Northern European countries, including France, Poland, and the UK. He analyzed both freshwater and marine aquariums, with aquarium sizes varying from 50, 200, to 400 liters. 

Results of the study

Based on the UK data, Dr. Perry’s research suggests that a tropical aquarium could produce a significant 85.3 to 635.2 kg of CO2 per year, depending on size and operational conditions. This equates to a considerable 1.6 to 12.4 percent of the UK annual average household CO2 emissions.

Moreover, the study revealed that tropical aquariums could consume anywhere from 156 to 31,200 liters of water per year. This consumption level translates to between 0.2 and 30.1 percent of the UK annual average household water usage, hinging heavily on the size of the aquarium and the maintenance routines employed.

The study identified two primary factors contributing to these environmental impacts: the energy required to heat the water – particularly in larger aquariums – and the varying levels of decarbonization in the electricity grids of different countries.

Environmentally conscious choices 

However, Dr. Perry stated, “Ornamental fish keeping can be a more environmentally conscious pet choice than owning an average-sized dog or cat, which are likely to produce considerably more emissions through their consumption of meat.”

At the same time, he cautioned that the environmental impacts of fish keeping could be substantial, varying with the aquarium size, operational methods, and even the country it’s housed in. “There are still improvements that can be made to ensure the environmental sustainability of the hobby.”

According to Dr. Perry, as national energy grids start to decarbonize, the environmental impact from the energy needs of keeping fish will improve. However, he warned that mitigating the environmental impact of high water consumption is a formidable challenge that requires individual-level ingenuity.

Dr. Perry’s research sounds an important environmental alarm, calling for greater awareness of our pet choices’ ecological consequences. “These are important considerations as we face a climate emergency linked with our demands for energy, as well as water insecurity linked with our demands for water,” he concluded.

The study is published in the Journal of Fish Biology.

More about pet fish

Fish have been a popular choice of pet for centuries. They offer companionship and a sense of tranquility, and their diverse colors, shapes, and behaviors can be mesmerizing. Fishkeeping can also provide a fascinating insight into aquatic life, and maintaining a balanced, healthy aquarium can be a rewarding hobby.

There are many types of pet fish, but they are typically divided into two categories: freshwater and saltwater fish. Freshwater fish are often seen as a good choice for beginners as they tend to be more adaptable and require less complex equipment than their saltwater counterparts. Common types of freshwater fish include bettas, guppies, goldfish, tetras, and cichlids.

Saltwater fish, while generally more demanding to keep, offer a unique range of species, many of which are brightly colored and known for their interesting behaviors. Some popular saltwater fish species include clownfish, angelfish, butterfly fish, and tangs.

Fish come in all shapes and sizes, from the tiny neon tetra to the considerably larger Oscar fish. Their lifespan can also vary significantly. While some species like goldfish can live for decades under the right conditions, others may only have a lifespan of a few years.

Fishkeeping involves more than just feeding your fish and changing the water occasionally. It requires understanding the specific needs of the species you’re keeping. Factors such as diet, water temperature, pH levels, and compatible species for cohabitation must all be considered.

As evidenced by Dr. William Perry’s research, fishkeeping is linked to environmental impacts such as high water consumption. Making conscious choices about the size of the aquarium, the number and species of fish, and maintenance routines can make a difference in mitigating these environmental effects.


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