Fish Don't Live in a Zombie State so Don't Treat Them Like They Do

aquarium fish

Story at-a-glance

  • Accumulating evidence is doing away with the notion that fish are unthinking, unfeeling beings
  • Fish can feel pain and stress, learn to do tricks, and they have excellent long-term memories
  • Fish are often viewed as simply “display animals,” but it’s important to provide adequate stimulation in the form of an enriched environment
  • Attention should be given to feeding, habitat, introducing new fish to the tank, lighting, exploration and more

By Dr. Becker

Did you know that fish can feel pain, or that they show emotions like anger by flaring their fins and nipping at other fish? Fish can “talk,” too, using a wide range of communicatory methods, including sound-evoking vibrations, booms, growls, thumps, whistles, and even bone rattling.

So while your aquarium fish may appear to be content to swim silently in circles in a fish bowl on your counter, this is really no life, even for a fish.

Fish Get Stressed Out Too, Especially When Their Habitat Is Lacking

Accumulating evidence is doing away with the notion that fish are unthinking, unfeeling beings. In 2014, Culum Brown, Ph.D., a professor in the Department of Biological Sciences at Macquarie University, published a review highlighting evidence that fish: 1,2 

  • Perform multiple complex tasks simultaneously (a trait that was once believed to exist only among humans)
  • Recall the location of objects using “feature cues” (which humans figure out how to do around age 6)
  • Have excellent long-term memories
  • "Cooperate with one another and show signs of Machiavellian intelligence such as cooperation and reconciliation”
  • Use tools

The subject of fish welfare is receiving increased attention as intensive “aquaculture,” or fish farms, become more popular.

From an animal welfare perspective, if an animal is sentient it’s generally assumed it should be offered some form of protection for its physical and mental well-being, which is currently lacking for fish.

Yet, as researchers wrote in Applied Animal Behaviour Science, fish deserve welfare considerations just like other animals:3

“Teleost fish [ray-finned fishes] are considered to have marked differences in some aspects of brain structure and organization as compared to tetrapods [vertebrate land animals], yet they simultaneously demonstrate functional similarities and a level of cognitive development suggestive of sentience.

Anatomical, pharmacological and behavioural data suggest that affective states of pain, fear and stress are likely to be experienced by fish in similar ways as in tetrapods.

This implies that fish have the capacity to suffer, and that welfare consideration for farmed fish should take these states into account.

We suggest that the concept of animal welfare can be applied legitimately to fish. It is therefore appropriate to recognize and study the welfare of farmed fish.”

Aquarium Fish Deserve to Have the ‘Five Freedoms’

Aquatic animals, including fish, are the most popular pets in the U.S. if you calculate popularity based on the number of owned pets.4

While fish are often viewed as simply “display animals” that are their for your viewing enjoyment, it’s important to provide adequate stimulation in the form of an enriched environment. A review published in the Veterinary Clinics of North America: Exotic Animal Practice journal noted:5

For a long time, there was debate over whether or not fish were able to experience pain or form long-term memories. As that debate has reduced and the consciousness of more aquatic animals is accepted, the need to discuss enrichment for these animals has increased.”

The review explains that fish in hobby aquariums, backyard ponds and aquariums should be afforded the five freedoms of welfare, which include:

  1. Freedom from hunger
  2. Freedom from discomfort
  3. Freedom from pain, injury or disease
  4. Freedom to express normal behavior
  5. Freedom from fear and distress

How to Help Your Pet Fish Flourish

In order to integrate these freedoms into your home fish tank, there are a variety of factors to consider. No one method will work for every tank, as aquatic species vary in terms of their needs for nutrition, housing, temperature, lighting, water quality and more. However, some basic considerations include:6


In addition to providing the proper food, consider the method of feeding. Some fish scavenge for their food while others hunt, for instance. Consider the use of puzzle feeders and sinking feeders, or live prey, if applicable to your fish species.

New Acquaintances

Before new animals are added to an existing tank, a quarantine period is recommended. To help relieve the stress during the quarantine, a hiding spot (such as PVC pipe or stacked rocks) should be provided and water quality and temperature should be maintained.

If you have newborns in your tank, they should be separate from adults immediately because infanticide is common in captivity. Further, the review authors recommends providing live food to newborns, as their mortality rate increases when they’re fed only dry food.


An important aspect of your tank is lighting, particularly natural light. Seek to provide varying intensity and wavelengths of light that are programmed to reflect seasonal changes, if possible.

You can also change out the furnishings in your tank seasonally to offer your fish new places to hide, hunt and explore.

Target Training

This is more applicable to fish in research settings, but if you ever need to provide your fish with medical care it will also benefit home aquariums. Target training involves training animals to come toward a specific target, such as a light or colored object.

A food reward is given when the fish contacts the target. According to DVM 360, “The training allows for less stress for medical interventions, weight checks or transport.”7

The goal of these interventions is happier, healthier fish and other aquatic species. According to the review:

“ … [E]nrichment programs are designed to decrease stress, increase natural behaviors, and by decreasing stress, decrease injury and disease.”

10 Tips for a Happy Aquarium

If you’re considering fish as a pet, only buy those that have been bred in captivity, not those taken from the ocean. Next, think about the type of fish you want and whether it lives well with other fish.

Betta fish, for example, can learn to recognize their owners and perform tricks, such as following your finger around the bowl, swimming through hoops, or pushing a ball into a goal.

And while male bettas cannot be kept together, a male betta can be kept in a community of fish (without other male bettas) and female bettas can be kept together.

When you’ve determine the right type of fish for your aquarium, here are additional steps that can help ensure your pet fish aren’t only surviving but thriving:

  • Provide ample space — at least 24 square inches of water for every one inch of fish
  • Provide a quiet pump and filter that keeps water clean and flowing
  • Install an air pump for oxygen and a thermometer to monitor water temperature (this should generally be between 68 and 76 degrees F, depending on the species of fish)
  • Provide non-toxic items for your fish to explore — plants, rocks, structures, ceramic objects, etc. Change them regularly to provide new stimulation.
  • Keep your fish in a quiet area away from loud televisions and radios, and out of direct sunlight
  • Provide the right type of food for your fish type (each type of fish may vary in their nutritional requirements)
  • Clean the tank regularly
  • Be careful not to startle your fish with sudden changes in lighting or noise
  • If your fish seems sick, take him to a veterinarian (along with a sample of tank water)
  • While some fish do better alone, most enjoy companionship and should be kept in pairs (or more)


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