Can Fish See in the Dark? This Is What Experts Say

The ocean is deep and gloomy in many areas. Certain species, like anglerfish, have evolved to survive in those environments by creating light, whereas other fish use different strategies. However, you might be asking if fish have night vision. We’re here to discuss the opinions of professionals on freshwater and saltwater conservation.

Additional Rod Cells

Fish have far better vision in low light than humans do, even though they can’t quite “see in the dark.” But that varies from species to species. High-sensitivity vision has evolved in several deep-sea fish species. That’s why they can see in nearly complete darkness.

Because they have more rod cells at the back of their eyes than humans do, almost all fish have greater night vision than humans. A multibank retina is a group of additional rods composed of up to 28 light-sensitive opsins. Fish living in lighter environments may have less vision, which is more akin to human eyesight, but fish living in deeper and darker conditions have evolved to have closer to 28.

Seeing By Feeling

Fish use their sense of touch to perceive and comprehend their surroundings, even in the absence of light. On both sides of their body are pressure-sensitive organs that detect even minute variations in water pressure. They can sense which way the pressure shifts as another fish passes by, alerting them to the presence of something nearby.

Using Bioluminescence

Fish species that inhabit deep ocean regions have evolved to their environment, allowing them to see with the help of other light sources. The subtle bioluminescence that is emitted by bacteria, octopuses, mussels, and other fish is one of those sources. Bioluminescence can be identified by the faint glow to fish’s scales or by the glowing green or blue eyes that you may have seen on fish. Fish that reside in deep water typically have this.

Even though it may not seem like much to you or me, a fish’s eye’s bright light may illuminate a vast underwater world. Research on deep-sea organisms has revealed that they generate amino acid sequences capable of detecting light at different wavelengths, such as those emitted by bioluminescence.

Fish in Aquariums and Shallow-Water Species

Fish like goldfish and bettas are examples of creatures that are blind in the dark. Like humans, they have limited night vision. Like humans, goldfish and betta fish sleep mostly through the night and occasionally take “naps” in the middle of the day. These and other common aquarium fish species typically cannot see in the dark any better than humans can.