7 Facts About Aquarium Fish Most People Don’t Know

Aquariums offer a serene glimpse into an aquatic world, a chance to bring a piece of the mysterious underwater universe into our homes and workplaces. But there’s more to these vibrant swimmers than meets the eye. 

Here’s a dive into some little-known facts about aquarium fish that might just make you see your finned friends in a new light.

1. They Can Recognize You

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Believe it or not, some aquarium fish can identify their owners. Studies have shown that some species of fish can distinguish human faces. (ref) When you approach the tank, it’s not just a race for food—these intelligent creatures are actually checking you out.

They notice who feeds them and can differentiate between familiar and unfamiliar people, reacting more excitedly or calmly when they see someone they recognize.

This recognition is not just about vision; it’s about the bond. Observations suggest that fish who are regularly interacted with show fewer signs of stress and may even be healthier. Their ability to identify different humans might stem from their need to understand their environment, a key survival trait refined by evolution.

2. Their Colors Can Change Based on Mood

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The vibrant hues of aquarium fish are not just for show—they can also indicate their health and mood. Certain species, like the neon tetra, adjust their coloration depending on their environment and emotional state. (ref) Stress can cause colors to dull, which is often a sign to owners that their aquatic habitat might need attention.

On the flip side, vibrant and colorful fish are good indicators of happiness and health. This dynamic coloration is due to specialized cells called chromatophores that respond to various hormones in the fish’s body. So, a brightly colored fish might not just be at its healthiest but also its happiest.

3. They Need Sleep Too

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Fish in aquariums do sleep, although not in the way humans do. They don’t have eyelids, so they can’t close their eyes. Instead, they enter a state of rest where they are less active, and their metabolism slows down. This rest is crucial as it helps them conserve energy and maintain their health. (ref)

Observing a fish’s sleeping patterns can be quite fascinating. Some will hover in place, others might nestle in a cozy part of the tank, and some even lie on the bottom. Ensuring they have a regular cycle of light and darkness is key to helping them establish healthy sleeping routines, just like us.

4. Their Memory is Better Than You Think

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The old myth that fish have a three-second memory is just that—a myth. Research has shown that many fish have impressive memories. Goldfish, for example, can remember training techniques for months. This memory ability is critical for navigating and adapting to complex environments, avoiding predators, and finding food. (ref)

This capacity for memory also means that fish learn routines. They can become accustomed to feeding schedules and even start to anticipate regular interactions with humans, which can make training them both possible and rewarding.

5. They Communicate Through Sounds

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Fish are more vocal than you might expect. They use a variety of sounds to communicate with each other, which can include clicks, chirps, and low-frequency pops. These sounds can convey different messages, from warnings of danger to expressions of dominance or readiness to breed. (ref)

The sounds are often too faint for human ears without special equipment, but they play a critical role in the social lives of fish. By communicating, they coordinate with each other and maintain social hierarchies within their groups.

6. Water Quality Is Critical to Their Health

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Water quality in an aquarium isn’t just about keeping the tank clean; it directly affects the health of the fish. Poor water conditions can lead to stress, disease, and even death. Parameters like pH, hardness, ammonia, nitrite, and nitrate levels must be checked regularly to ensure they are within safe ranges. (ref)

Good water quality mimics the natural habitat of the fish, which helps them thrive. Regular maintenance, including water changes, checking filtration systems, and monitoring water conditions, can keep these aquatic pets healthy and vibrant.

7. They Can Benefit from a Varied Diet

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Like many pets, aquarium fish thrive on a varied diet tailored to their species-specific needs. While some fish are carnivorous, requiring a diet rich in proteins, others are herbivorous and do better with plant-based foods. Omnivorous fish require a mix of both. Offering a variety of foods can prevent nutritional deficiencies and promote a stronger immune system, enhancing both their coloration and vitality. (ref)

Incorporating different types of food not only meets the nutritional requirements but also stimulates the fish mentally, making feeding time an engaging part of their day. 

For example, some fish enjoy hunting live food, while others may prefer foraging for food particles in the substrate, mimicking their natural feeding behaviors. This variety ensures that all fish can engage in the feeding styles that are instinctual to them, contributing to their overall well-being and longevity.

Embracing these facts not only enhances our understanding but also our appreciation of these fascinating creatures. By learning more about their world, we deepen the bond between us and our aquatic companions, ensuring they lead happy, healthy lives in our care.

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Davin is a jack-of-all-trades but has professional training and experience in various home and garden subjects. He leans on other experts when needed and edits and fact-checks all articles.