The Eco Fish Tank: 6 Ways To Reduce Your Carbon Finprint

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Most fishkeepers are animal lovers and don’t realize that their hobby can have an impact on the environment and the natural habitat their beloved pets came from.

In this post I’ll discuss the impact of fish catching and farming practices, energy consumption from fish tanks, krill fishing to make fish food and many other factors, as well as how how you can make your fish tank as eco-friendly as possible.

Are fish tanks eco friendly?

Keeping fish is getting more sustainable all the time, aquarium owners can make their setup more eco-friendly in a few different ways. Key considerations include the impact of both wild-caught and farmed fish, the energy demands of your tank setup and even the type of food given to your fish.

Is keeping fish bad for the environment?

There are several ways that fishkeeping is, unfortunately, damaging the planet. From cyanide fishing damaging coral reefs to the energy needed to constantly power a tank in your home, fishing has a carbon footprint that is an inconvenient truth for many hobbyists.

Coral reef damage

It starts with how they’re often caught, which is harmful to both the fish themselves and the coral reefs in Southeast Asia where they’re found. Divers mix crushed cyanide with seawater in spray bottles, which they use to stun fish hanging around coral reefs to make them easier to catch.

Not only does the cyanide damage the reef directly, but when the fish then retreats into the coral the divers break apart the reef to extract them. Coral reefs are vital for the health of the ocean and are being destroyed by commercial fishing and irresponsible collectors.

According to

Because of the diversity of life found in the habitats created by corals, reefs are often called the “rainforests of the sea.” About 25% of the ocean’s fish depend on healthy coral reefs. Fishes and other organisms shelter, find food, reproduce, and rear their young in the many nooks and crannies formed by corals.

What makes the situation worse is that this method is a numbers game. Divers often don’t just ‘stun’ the fish but kill them, and simply see this as collateral damage as long as they meet their catch quota. For anyone who cares about the fish they keep, this must raise a serious concern about what could have happened had your beloved pet not been one of the lucky ones.

Energy consumption

Despite our efforts to use more sustainable sources of energy, we are in the midst of an energy crisis that threatens our way of life as we know it. Simply put, the planet isn’t equipped to handle the rising population of humans and the rate we’re using up our natural resources.

According to, about 60% of total electricity generation in the US in 2020 was produced from fossil fuels, producing greenhouse gases which are contributing to climate change and causing acid rain which is devastating to wildlife.

Meanwhile, we use that same electricity in our homes to power our tanks. Whether it’s a filter that needs to constantly maintain the water or the lighting feeding our plants, aquariums use plenty of power.

And that’s just low-tech freshwater aquariums. Saltwater aquariums are even more power-hungry, with the tank, heater, return pump, lighting, dosing pump, protein skimmers and powerheads all needing juice to keep running. This comes at a considerable cost to the owner’s carbon footprint.

Why is fish farming bad for the environment?

In an article on Petco’s website, Dr. Judy St Ledger of Rising Tide Conservation argues that “Sustainable is a subjective term” and Petco state that ‘95% of the freshwater aquatic life sold at Petco is aquacultured while 35% of the marine aquatic life sold at Petco is aquacultured’. (Aquaculture is basically breeding fish for sale).

But what are the negative effects of fish farming? While aquaculture prevents the damage to reefs and interruption to the food chain described above, PETA point out that there are other environmental considerations, such as the ‘waste, pesticides and other chemicals’ being released into coastal waters from fish farms, or aquafarms.

This article describes how Brazilian aquaculture operations were forced to close due to the impact on the numbers of the country’s marine life. This is why fish farms are bad for the environment, despite their purpose being to avoid damaging wild ocean ecosystems.

Meanwhile, London-based activist group Sustain comment that farmed fish can carry disease and parasites such as sea-lice, which ‘can spread these to their wild counterparts, affecting the health of wild populations near fish farms’.

(Note: this chart relates to seafood production as fish farming is also a significant part of the food industry and does not only apply to the farming of fish for aquariums)

Is fish food eco-friendly?

Not do pet stores sell fish that are caught in unethical ways, but other fish are also caught to produce the food that we give to them. This impacts the natural balance of the ocean ecosystem, as it takes species like krill out of the food chain, where they provide essential sustenance for whales, seabirds, and other marine life.

In 2009, NOAA banned Pacific krill fishing within 200 miles of California, Oregon and Washington in an attempt to keep ocean life and biodiversity thriving. In 2019 there was a wider call from Greenpeace for krill-fishing companies to “restrict all fishing activity, including transhipments, in areas under consideration by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) as ocean sanctuaries and in any areas protected under the Antarctic Treaty.”

This followed concerns in their report, ‘License to Krill’, over what the organization called ‘illegal, unreported and unregulated (IUU) fishing’. In Antarctica, penguins and other local species are being impacted by krill fishing, with one of the main products being food for salmon farms and home aquariums (source).

This means that while doing their best to choose a healthy, nutritious diet for our pets, we’re inadvertently contributing to the destruction of food sources for many ocean species. This is something we must take incredibly seriously as the damage to biodiversity in our oceans threatens the future of every form of life on our planet.

Is it cruel to have a fish tank?

Despite what we’ve been led to think fish are intelligent and experience stress and fear just like us. Nobody should keep a fish just for decoration; they’re as much a responsibility as your pet dog and deserve a good life.

Of course, the best life for a fish is in an ocean or river, and fishkeepers need to make their own decision how comfortable they are with their contribution to taking these animals out of their natural environment.

Fish live longer in the wild on average, and anyone choosing to keep them in an aquarium should make every effort to give them the best life possible and to look after their health. If your pet fish is no different to a lamp or an ornament, please don’t buy one.

Do fish suffer in tanks? Well, fish get bored living in an empty tank and ultimately this impacts their physical health, so always make sure you research what your fish needs to live a long, happy, and healthy life, with a good diet, plenty of stimulation and optimal living conditions.

“Rainbow” loves exploring these barrels. Note: never let your children name your fish.

Is keeping fish ethical?

There are pros and cons in the debate around the ethics of keeping fish, and while the negative impact does seem to outweigh the positives, there are ways for fishkeepers to be more ethical when choosing where their fish is sourced, the type of fish they keep, and the environmental impact of their tank setup.

On the plus side, the industry provides income for fishermen and fish farmers in poor parts of the world, and keeping fish can promote consciousness of animal welfare and empathy with fish and other animals amongst children and adults alike.

Fishkeepers should always consider the energy demands of running a fish tank, damage to coral reefs and other environmental concerns and take steps to minimise this impact, as discussed below.

There’s also the high proportion of deaths in wild-caught fish vs pollution from fish farms – there’s really no completely environmentally-friendly way to source aquarium fish and this is something all fishkeepers need to be aware of.

Of course, we know that on average fish don’t live as long in captivity, so we should all make every effort to maximize the quality of life of our fish by ensuring we have the optimal tank setup for their health and happiness.

How can I make my fish tank eco-friendly?

While Petco have made strides to rely more on aquaculture to source fish rather than disrupt the natural ecosystem, PETA insist the only way to have a 100% eco-friendly fish tank is not to have one at all. However, there are ways for fishkeepers to be kinder to the environment.

Here are 6 ways to reduce your carbon fin-print and help the environment as a fishkeeper:

1. Go for a smaller tank

While I’d never encourage anyone to keep fish in a tank that’s too small, planning ahead could mean skipping out on that huge, high-maintenance monster of a tank if all you’re going to need for the fish you choose is a 30 gallon.

Read more: Neon Tetra Tank Size: Everything You Need To Know

The bigger the tank, the more water is needed for water changes and the more powerful a filter setup you’ll need to keep the water clean and hospitable for your fish. Plus, if your partner is anything like mine, you’ll have a better chance of getting permission to bring home a small tank in the first place!

2. Choose an energy-efficient tank setup from day one

It sounds obvious, but how many of us knew what we were doing when we bought our first tank? Often, we take what is recommended to us by our local fish store and are left with a tank that’s far from ideal, either for the fish we eventually decide we want to keep, or for the planet!

Doing your research in advance is key to any successful setup, and the environmental impact of your setup should be a major consideration.

Choosing high-output LED lighting instead of the older-style, high-wattage lamps can make a massive difference to your energy costs, and as I’ll explain below, the right filter can make the whole setup much more energy efficient.

New 40 Gallon Long Tank‘ by jprime84 is licensed under CC BY-ND 2.0.

3. Reduce the energy demands on your filter with a clean-up crew

One of the biggest energy drains in any aquarium is the filter, which has to constantly pull in water and expel it back into the tank. If the water is particularly contaminated, this puts a strain on your filter that has a knock-on effect on the amount of energy needed to maintain this constant cleaning routine.

Enter the clean-up crew – snails and shrimps that will dramatically reduce the demands on your filter.

Nerite Snails, for example, are amazing algae eaters. Watching their little teeth scrape green algae from the sides of the glass is a hypnotic experience, and they’ll gladly munch on any leftover food your fish let float down to the substrate.

Another bottom-feeder that will be delighted with leftovers are shrimps. There are amazing, colorful species like Red Cherry Shrimps, Yellow Fire Shrimps and Blue Diamond Shrimps that will get into every crevice in your tank where small bits of food and fish poop settle (yes, they’ll eat that too!). All this cleaning means less strain on your filter, making it more energy efficient and less likely to fail.

My personal favorite is the Amano Shrimp, who are constantly snacking on the blackbeard algae that has decided to appear in my community tank. They seem less shy than other species, are always busy cleaning up after their tankmates and are big enough that the likes of the khuli loaches in my tank won’t see them as a snack!

4. Use your dirty tank water to water your plants

I started using the water from my tank changes a while back and my plants have never looked healthier. Instead of pouring it down the sink, keep it in a bucket and store it for later use on your plants – whether this is for your indoor houseplants or your garden, I promise you’ll see the difference!

Fish poop in the water acts as a natural fertilizer, no different to farmers using manure in their fields. After I’ve vacuumed the substrate or changed the filter, the leftover water gets good and filthy, and the dirt collects in the bottom of the watering jug. A quick mix before watering and you have the perfect plant food!

My plants are doing great thanks to my used fish water!

Even better, by recycling your fish water there’s no need to collect additional water from your tap. Before it gets to your home, water goes through a number of processes that all use up a huge amount of energy. Wasting water should be something we all look to avoid at all times, let alone for the sake of watering plants just for decoration.

Note: saltwater kills plants, so don’t do this if you have a saltwater tank! Which brings us to the next point…

5. Choose a freshwater tank

Even though a saltwater tank gives you lots of exotic options for livestock, it’s difficult to justify the additional energy usage needed to maintain this setup. According to The Guardian, “A large reef tank containing live coral and a wide range of fish species could get through several thousand kWh a year. Meanwhile, a small freshwater tank could consume as little a 150kWh over a year.” This is both due to the additional equipment needed as well as the size of the tank.

Choosing a freshwater tank dramatically lowers the electricity consumption, especially if you go for cold water fish that don’t need a heater to maintain a higher temperature. Of course, you should never sacrifice the fish’s health for any reason including energy consumption, so here’s a list of freshwater species that live at colder temperatures (I’ve listed 10 but there are lots more!):

  1. Goldfish
  2. Celestial Pearl Danios
  3. Endler’s Livebearers
  4. Bloodfin Tetras
  5. Buenos Aires Tetra
  6. Dojo Loaches
  7. Rainbow Goodeids
  8. Black Moors
  9. Guppies
  10. Meteor Minnow

6. Choose a more eco-friendly fish food

Right now this can be hard to find, especially as a Google search for something like ‘eco-friendly fish food’ returns results like ‘Which fish is sustainable to eat?’

Thankfully, there are efforts being made in the aquafeed industry to make the jump to more sustainable ingredients. Oils and meal from fish and terrestrial crops (which create dietary imbalances) are being replaced by ‘circular’ components made from different types of waste.

According to this article from All About Feed, foods created from bacteria and microalgae are the future, but right now you can buy insect-based fish food that is rich in oils and protein. Brands like Friendly Fish and Ynsect are revolutionizing aquaculture, and I’m already using Fluval Bug Bites to feed my Betta (although this still contains Salmon as well as being insect-based).


Even though the best way for fishkeepers to protect the environment is to not keep fish at all, there are lots of ways to make your setup more eco-friendly.

What’s even better is that all corners of the industry are finding ways to make our hobby more sustainable – from replacing power-hungry bulbs with LED lighting to new sources of aquafeed, the decision to keep fish in an aquarium is becoming easier for eco-conscious owners.

Main image: “Coral Reef, Florida” by Jerry Reid is licensed under CC BY-ND 2.0.

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