Do Fish Have Eyelids ? | Fishinaquarium

Do Fish Have Eyelids


Do fish have eyelids? This is exactly what comes to our mind when we look at the wide-open eyes of these water-living cuties. Isn’t it? Well, their eyes are quite a unique part of their anatomy, which sets them apart from other living species.

However, the answer to your question, do fish have eyelids, depends on the species. The majority of fish species do not have eyelids as they don’t require them. But some fishes like sharks, milkfish, etc., do have them. Their transparent eyelid allows them to see through it clearly.

Do fish have eyelids?


Well, the quick and easy answer to it is no, they don’t have eyelids. It is hard to find a fish, which has an eyelid like humans and blinks its eyes like us.

Most fishes do not have any eyelids simply because they do not require any. Therefore, there is no need for them to have eyelids.

The primary purpose of eyelids is to keep our eyes moist so that it doesn’t dry out. Also, eyelids protect our eyes from harsh elements in the air, such as dust, dirt, or other microscopic particles, which can be harmful.

But fishes do not have to face any of the above situations. As they always dwell in the water, neither their eyes get dried out, nor there is any threat of entering dust or dirt particles from the air into their eyes.

However, if you want an in-depth answer to the question, do fishes have eyelids, then let us tell you most fish species do not have any eyelids, but there are a few exceptions. Some fish species do possess transparent eyelids over their eyes.

Why do fish not have eyelids?

Well, as said before, most fishes do not have eyelids because they do not require any. There is no threat for fish’ eyes to get dried out due to lack of fluid, as their eyes are always in contact with water.

Besides, the water fishes reside in is mostly free from potential dirt or dust particles, which can float along to enter into their eyes. Hence, they do not require this sense organ in their anatomy.

Why do some fish have eyelids?


However, just in contrary to the previous section, there are still some fish species that do possess some special kind of eyelids. A few fishes just have a protective membrane over their eyes, while some come with a fatty adipose eyelid.

Nevertheless, eyelids are present on some fish’ eyes to serve special purposes. These eyelids help their eyes have a better focus on objects so that they can easily avoid obstacles underwater and move swiftly. Also, it protects their eyes from any foreign object in the water.

Why do fish have transparent eyelids?


Well, some fishes possess transparent eyelids, which cover their eyes partially or fully to let them see better under the water. These eyelids often work as a lens, which offers them a clearer and more focused vision.

Besides, the transparent eyelids present in the eyes of some fish do not allow them to blink quite often; thus, making them monitor their surroundings more vigilantly.

What fish have eyelids?


As we have said earlier, there are some fish species, which do have eyelids. But now the question is what fish have eyelids, what are their names.

Well, there are many exceptional cases where you can find some fishes to have eyelids, and they flaunt their eyelids in many styles. How cute, isn’t it?

Well, fishes like sharks possess a protective nictitating membrane, which acts as eyelids over their eyes. On the contrary, some fishes have thick and transparent eyelids, which helps them see through it. According to scientists, these special eyelids on the eyes of some fishes are more like glasses. It helps those fishes to have a better focus on objects.

These transparent eyelids are known as adipose eyelids, which are found in some fish species. It usually covers some or all areas of their eye.

You can mostly find adipose eyelids in deep-sea benthic fishes. However, it can also be seen in some non-benthic fish. The fishes that come with eyelids are iso spondyls, milkfish, mackerel, jacks, and mullets.

These adipose eyelids in the fish may act as a lens to help them have better vision. Also, sometimes it gives them the capability to see polarized light. It may even block ultraviolet light from penetrating their eyes. Moreover, it is assumed that these eyelids may serve as a physical barrier to protect fish’ eyes from unfamiliar objects in the water.

Do bony fish have eyelids?


Now, when it comes to bony fish, they tend to possess some unique features in their eyes. Usually, these fishes have well-developed eyes with which they can have a complete 360-degree clear vision.

However, unlike sharks, bony fishes do not have eyelids. Nevertheless, some of them have a false eyespot on their tails, which are used for confusing predators.

Do betta fish have eyelids?


Well, we all know that betta fishes have the habit of sleeping to take rest and maintain a healthy living. And based on this fact, it is very obvious to think, do betta fish close their eyes while sleeping. Also, you might wonder, do betta fish have eyelids.

Well, the answer to both of your questions is no! Though betta fishes sleep, they do not close their eyes because they do not have eyelids to shut their eyes. In fact, you can find them sleeping peacefully and motionlessly while keeping their eyes wide open in the tank.

Why do betta fish eyes pop out?


Have you ever seen the eyes of bettas pop out? Maybe yes! Then you might think, why do betta fish eyes pop out, isn’t it?

Well, that’s because your betta fish is suffering from popeye. It is a kind of infection that can often be seen in bettas. Most of the time, various bacterial or fungal infections cause popeye in bettas.

Popeye can occur in both the eyes of your betta fish. This infection is primarily visible in bettas that live in community aquariums and stay in close contact with other fishes having the popeye syndrome. This eye infection is highly contagious and spreads rapidly. So, if you notice your betta or any other fish to have contracted popeye, then treat them immediately.

Do goldfish have eyelids?


Do you know similar to betta fishes, even goldfishes sleep in the aquarium? Well, then again, the same question is expected to come to your mind, do goldfishes have eyelids.

But unfortunately, in this case, too, the answer will disappoint you. Even goldfishes do not have any eyelids. So, if you ask, do goldfish close their eyes, unlike betta fishes, the answer would again be a no. Since they lack eyelids, there is no way for them to close their eyes. Obvious, isn’t it?

Whenever they find the aquatic environment quiet and comparatively dark, they tend to sleep at the bottom of the tank with their eyes wide open.

Do pufferfish have eyelids?


Did you just see your pufferfish blinking? Well, don’t worry, you saw that right! Pufferfishes are the only bony fish that are capable of closing their eyes. Thus, it’s obvious to wonder, do pufferfish have eyelids.

But the truth is that they do not have any eyelids. So, pufferfishes tend to blink much differently without using any eyelid.

They usually sink their eyeballs deep into their sockets. Then, these fishes cockle the skin around their eyes.

As per studies, pufferfish exhibit a blink-like response when jets of water come towards their eyes. But do you what’s more interesting about pufferfishes? Their eyes close in a much circular motion, unlike eyelids that usually move horizontally or vertically.

Do clownfish have eyelids?


Similar to most fishes, clownfish also do not have any eyelids over their eyes. They simply have a clear vision from their wide-open eyes all the time.

Since they do not have any eyelids, they also cannot close their eyes, unlike land mammals.

Do pleco fish have eyelids?


Are you wondering, do fish have eyelids that belong to the plecostomus species? Well, like any other common fish species, even plecos do not have any eyelids over their eyes. Hence, they cannot close their eyes like other animals.

How do fish sleep if they have no eyelids?


The sleeping behavior in fish is much different from any other species. You will not find the fishes to close their eyes while sleeping. Hence, it is pretty difficult to recognize if your fish is sleeping or awake.

However, they do sleep in their way. Fishes have their own way of sleeping while keeping their eyes wide open. They usually tend to stay motionless while sleeping. Also, you can find their gills to move very slowly while they are asleep.

Whether your aqua pet is a nocturnal one or a night-sleeping one, it will sleep with its eyes open and slow-paced breathing due to reduced brain functioning. They can barely respond to any activity happening around them while sleeping.

Also, some fish prefer to sleep hiding at a safer place with reduced swimming to save themselves from any predator.

Wrap up


So, by now, we hope you must have got the right answer to your query, do fish have eyelids. While most of them lack eyelids, a few fish species do carry a special type of eyelid.

However, you better not expect it from any common fish species you come across regularly. As discussed above, this unique feature is limited to only some special fishes that need it.