Discovering the Deep Depths: Can Fish See in the Dark?

I know you are looking for the answer to the question, ”Can fish see in the dark?” Yes, fish can see in the dark water.

The lateral lines of a fish act as its secret senses, helping it to sense its surroundings in the deep darkness of the deep water.

As fish cannot see in low light conditions, they have pressure-sensitive organs found on both sides of their body, that help them in navigating in dark waters or during darkness. The term used to refer to this is “lateral lines“.

Fish see light differently than humans. Yet, they can sense wavelengths of light in water and have an eye for light/dark cycles that reflect the natural day and night.

Can fish survive in deep darkness?

While several deep-sea fish have adapted to survive in complete darkness, aquarium fish require light. This especially relates to living things that inhabit deep oceans near the light.

Light, like sunshine and vitamin D, helps fish in aquariums keep their bright colors and helps their immune systems.

Since the majority of fish do not feed or swim at night, the passage of light signals to your fish when it is time to swim, eat, or play. Like humans, fish also follow the natural day-night cycle according to light and shade.

The fish would constantly think it was sunset if kept in complete darkness, which might lead to stress and illness.

Consider how you would react if you were completely blinded at all times.

“Experts suggest that fish should never be kept in total darkness,”

Do fish are nervous in total darkness?

No. Although fish can be surprised by sudden changes in their aquarium’s lighting, they prefer darkness.

Instead, the arrival of night signals to your fish that it is time for them to go to sleep.

The only time nocturnal fish feel safe emerging from hiding to feed and play is during the night.

Do fish require darkness during the night?

Affirmative. Fish require a minimum of 10-12 hours of darkness per day to allow for enough rest.

During periods of darkness, fish enter a condition of inactivity that closely resembles sleep.

They perform a behavior known as “resting” with their eyes open but keeping in response to factors outside, such as light. Hence, it is crucial to ensure that the lights always switched off.

If your fish does not get a minimum of 12 hours of darkness, it will become tired and bored in its environment. Also, you might observe your fish in a state like a trance during the daytime.

Fish, like a lot of animals, require both day and night cycles, as well as changes in light and darkness, to sustain their survival.

Even fish that are active during the night require darkness to signal their activity period.

Is it possible to feed fish in the absence of light?

Fish show feeding behavior in response to their hunger, but, they encounter challenges with detecting food under low light conditions.

However, fish that are active during the night have a preference for feeding in low-light conditions.

Ultimately, it is necessary to get to know yourself with the preferences of your fish and provide them with appropriate food.

For example, some catfish and certain plecos show a night feeding behavior, but a majority of aquarium fish have a diurnal feeding preference.

Be sure that your fish will eat food when hungry, although you may encounter an increase in leftover food debris if you feed your fish at a wrong time of day.

Are fish attracted to aquarium lights?

can fish see in the dark

Aquarium lights provide the dual purpose of increasing visibility of fish and promoting the growth of aquarium plants.

However, every species has specific lighting preferences. For example, some fish indicate a sensitivity to strong light, but nearly all fish show a preference for lighting that closely resembles their native environment.

Ensure that you consistently switch off your lights for a duration of 10 to 12 hours daily.

To view nocturnal fish without disrupting their sleep/wake cycle, it is advisable to put a night light or moonlight.

Moreover, fish universally detest abrupt alterations to their surroundings.

Prior to activating the lights in your aquarium, ensure that the curtains are open or the lights in the room are turned on, allowing your fish sufficient time to adapt.

When the moment arrives to switch off the lights, begin by turning off the most intense light source and let the ambient light to gradually diminish.

To ensure that your fish can rest correctly, you can easily shield your fish tank with a towel or blanket when it is time for sleep, especially if it resides in a setting such as an office or any other place where lights are constantly illuminated.

How do fish behave in darkness?


Most of the fish enter a state of rest during times of darkness. However, nighttime fish maintain a consistent day and night cycle, unaffected by changes such as daylight savings time.

However, specific changes differ in different fish species, and not all fish possess excellent vision in darkness. Some deep-sea fish show highly specialized capabilities to survive in total darkness, whereas fish in deeper waters may depend on alternative senses like lateral lines or electricity to navigate and find food in a lack of light.

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