Pet Keen is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Home > Fish > Are Small Fish Tanks Cruel? Vet-Approved Info

Are Small Fish Tanks Cruel? Vet-Approved Info

Male betta fish

Vet approved

Dr. Luqman Javed Photo

Reviewed & Fact-Checked By

Dr. Luqman Javed

Veterinarian, DVM

The information is current and up-to-date in accordance with the latest veterinarian research.

Learn more »

When it comes to the size of the fish tank you need, there are differing opinions. In fact, most people have their own ideas about what constitutes an appropriately sized fish tank. Many of these opinions are rooted in outdated beliefs and practices that do not account for things like modern fishkeeping equipment and a fish keeper’s commitment to the care of their fish. There is nothing inherently cruel about a small fish tank, but it is important to consider your fish’s wellbeing. To understand how to choose the right size tank for your fish, you first need to understand the facts (and the fiction!) surrounding choosing a fish tank.


Are Small Fish Tanks Cruel?

There isn’t an easy answer to this question, unfortunately. When it comes to the rules surrounding fish tank sizing, people will tell you things like one gallon per inch of fish in the tank, while others will tell you that no tank under 10 or 20 gallons is large enough for any fish.

The true answer to this question is simply this: it depends. Your fish should have adequate space to swim without obstructions. Some fish like more space than others, so make sure to read up on the wild habits of the fish you’re keeping. Some fish will keep to one space in the tank while others will happily swim laps around the tank multiple times per day.

A small fish tank can be cruel if your fish doesn’t have proper space to move, and they can also be cruel if you are not maintaining high water quality. Providing adequate filtration and performing regular tank maintenance will help maintain the water quality in your tank, thus keeping your fish happier and healthier. If you are not willing to put the time and effort into a proper tank setup and maintaining the water quality, then yes, a small tank can be cruel to your fish. If you are maintaining a healthy tank ecosystem and your fish has space to move, then a small tank isn’t cruel.

Image By: panpilai paipa, Shutterstock

How Do I Know My Fish Is Stressed?

The biggest indicator of whether your tank setup is cruel or not is to assess your fish for signs of stress. However, fish don’t experience or exhibit stress in the same way that humans do. This means that you can’t apply your human perceptions of stress to your fish.

Stressed fish are prone to illnesses because the stressors of their environment suppress their immune system. This means that if your fish is stressed in their tank, they may get sick more often than a fish in a stress-free environment might.

Fish will also exhibit specific behaviors that indicate stress.

These signs can include:
  • Fin clamping
  • Bottom sitting
  • Lethargy
  • Lack of appetite
  • Poor growth or weight loss (their spine might appear bent)
  • Color changes
  • Unexplained aggression towards tank mates
  • Glass surfing
  • Easily or frequently becoming ill

There are a variety of signs that indicate specific illnesses, so always investigate any unusual changes in behavior or appearance you notice in your fish.

Pink Betta Fish
Image By: gogorilla, Shutterstock

Is It Harder To Maintain a Small Tank?

It isn’t always more difficult to maintain a small tank, but once again, it totally depends. The size of the tank compared to the stocking of the tank is a huge factor. After all, a 55-gallon tank isn’t a small tank, but if you have 40 goldfish in it, then you’re going to have a huge commitment to cleaning and maintenance.

If you are keeping a small tank, it is important to ensure that you have adequate filtration for the size of the tank and the number of animals in the tank. This means that if you have a 5-gallon tank with multiple fish in it, then you may need a 25-gallon filter to maintain a healthy, clean environment in the tank. Understanding the bioload of the fish you keep is essential to choosing proper filtration since fish like goldfish produce a much heavier bioload in a tank than a Neon Tetra.

A smaller tank can be more of a time commitment than a larger tank, but with proper filtration and stocking, that may not be the case. Smaller tanks can require more frequent water changes than large tanks do, but that is fully dependent on the filtration available in the tank and the stocking of the tank.



In Conclusion

There just isn’t a simple answer to how cruel or not cruel small fish tanks are. However, it’s important to realize that a smaller tank can be a bigger time commitment, especially if the tank is overstocked or the filtration is inadequate.

There is nothing inherently cruel about a small fish tank, but it is important to consider your fish’s wellbeing. Ask yourself if your fish has enough space to swim in a way that is unobstructed and helps prevent muscle atrophy. Ensure your small tank isn’t overtaken by décor and plants that can take away from the limited space available to your fish. Aim for checking your tank’s water parameters at least twice a month, if not weekly, to ensure the water quality is appropriate and the filtration system is doing its job correctly.

Featured Image Credit: YanCabrera, Pixabay

Our vets

Want to talk to a vet online?

Whether you have concerns about your dog, cat, or other pet, trained vets have the answers!

Our vets