Can Fish Eat Chocolate? – Why Or Why Not?

Unlike dogs or cats, fish owners can’t share their favorite snacks with their pets. But that doesn’t stop owners from trying and sharing treats with the fish. And it includes chocolates as well. But the question is: can fish eat chocolate?

Fish can eat chocolates and digest them without much hassle. But, feeding chocolates too many times can cause major organ damage. The illness can range from constipation, fatty liver, and damage to the kidney and respiration system.

Fish accept food very easily. But it’s your job to check the food ingredients before feeding them. Below we will explain whether fish can eat chocolate or not. If not, then why exactly is it harmful to the fish?

So, if you own a group of fish or are interested in overall fish health, stay tuned.

Can Fish Eat Chocolate?

Fish will eat chocolate. But that doesn’t mean it’s good for them. They will eat and digest it like any other fun treat you give them. However, the ingredients in a bar of chocolate will slowly affect the fish organs.

Can Fish Eat Chocolate - Why Or Why Not

Especially, livers, kidneys, and heart would be at great risk of contamination. That being said, you are not the only person who has ever thought of feeding chocolate to their aqua pets.

In fact, a 15-inch Gourami in a London aquarium was brought up entirely on Kit Kats. So much so that the fish refused to eat any natural food later. It’s hard to believe, isn’t it? Luckily, the staff found a way to help the fish switch to a healthier and more natural diet.

5 Reasons Why Feeding Chocolate To Your Fish Is A Bad Idea?

Knowing how chocolate can affect fish health might convince you to avoid it. So, we are here with five major ways chocolate can harm your water pets. Take a look.

5 Reasons Why Feeding Chocolate To Your Fish Is A Bad Idea

1. Reduction In Oxygen Level

The number one disadvantage is that dissolved chocolate will reduce the oxy-level of the water. But how?

Well, chocolate bars are made with sugar and cocoa. Once these ingredients mix with water, the solution becomes perfect for other micro-bacteria to grow. For example, yeast, E.coli, and other micro-organs can easily be grown when the water is sugary.

And all these new tank members will consume oxygen along with the fish and plants. But the difference is that, now, your pets have less oxygen for themselves as most of the oxygen is consumed by bacteria to grow.

If you delay the water cleaning session, your fish will have difficulty breathing due to all the new intruders.

2. Fatty Liver

Just like humans, fish must avoid food with a high-fat level. Even carnivores who love meat should not eat anything with more than 10% of fat. And the number is only lower for herbivores (3-4%).

On the other hand, chocolates are a great source of saturated fat. Even though Omega-3 and 6 are essential for liver health, saturated fat is not the right substitute.

If you keep feeding choco-bars to the water pets, soon they will have fatty liver. It will affect their digesting ability. Not just that, fat has a direct and negative impact on heart health as well.

According to experts, regularly feeding chocolate can cause the fish to die sooner.

3. Dehydration

More than 30% of any chocolate is sugar. Now, sugar doesn’t affect the Ph level of water much. But it does something far more dangerous. You see, once chocolate dissolves into water, the concentration gets thicker than normal.

And, then starts the osmosis process. If you don’t know what osmosis is, it’s a mechanism where low-concentrated liquid travels towards high-concentrated liquid for balance.

The same thing happens inside the fish tank as well. Unfortunately, all the water inside your fish’s body and plants will come out due to osmosis. As a result, the living beings inside the tank will suffer from severe dehydration. That sounds terrible.

It doesn’t matter whether you own a koi or a betta. Every fish needs to be hydrated to live and thrive. And it looks like the sugar within the chocolate bars will mess with the system.

4. High Calories

Another major reason is the nutritional value of a chocolate bar. You see, fish need different kinds of vitamins and minerals as well. However, chocolate contains none of them. In that aspect, chocolate is not a good food for humans as well.

But the irony is that even though it contains zero nutritional value, the calories are extremely high. So, it makes sense that fish might lose their appetite for a healthy diet after devouring a small piece of chocolate.

So, not only are the fish deprived of helpful vitamins and minerals, but they don’t feel the urge to find something healthy anymore.

5. Polluted Water

Chocolate can pollute the tank water in two ways. First, the water becomes cloudy. We all know how important it is for fish to have a crystal-clear tank. Polluted water is a big cause of death among fish.

Another way of pollution is by adding toxins to the water. Chocolate contains metal elements like lead, cadmium, etc. Human bodies can fight against these toxins to a level.

But fish are extremely vulnerable to such kinds of metals. The consequences can be bad if those elements get inside their liver and kidney.

Some health issues your water pets might face are constipation, depression, damaged kidney, weak bones, etc.

Is There Any Human Food You Can Feed Your Fish?

After seeing so many negative impacts of chocolate, you might think all human food is bad for fish. But that’s not true. Aquarists share human food with their pets all the time. You only have to understand which food is good for the fish’s digestive system.

Is There Any Human Food You Can Feed Your Fish

Here, we will discuss some human food items you can share with your water buddies. Have a look.

1. Meat-Eaters/ Carnivores

The most famous carnivorous pet fish are the angel, Oscar, and Discus. We see these species almost in every community tank. These small predators love a small piece of meat.

So, if you are having steak for dinner, go ahead and share some with your pets. But, it’s not entirely healthy for them. Because beef or meat contains quite a heavy amount of fat. But occasional treats should be fine.

Moreover, if you own shrimps, put an egg yolk inside the tank from time to time. Shrimps find hard-boiled yolks super delicious, which is a good protein source for them.

2. Veg-Eaters/Herbivores

Parrotfish and Surgeonfish are two among the many herbivores. Their favorite food is reef algae. So, if you own herbivores, decorate the tank with lots of plants and algae.

That being said, you can also entertain herbivores with some human food. For example, peas, carrots, and spinach are great sources of nutrition. But make sure to boil the veggies. So, the food is soft enough for your aqua friends.


Need more feeding tips for your little ones? Check out our FAQ section for more information on this topic.

Is Sugar Bad For Fish?

Sugar is considered harmful to humans. It only makes sense that fish will be even more vulnerable to sugar. First of all, sugar helps to draw out the water from plants and fish causing dehydration. Not just that, sugar can help harmful bacteria to grow inside the tank and pollute it.

What Human Snacks Do Fish Like?

Most fishes love to eat human snacks. You can let your pets try cucumber, watermelon, orange, carrot, and peas. The list goes on. Of course, each fish comes with a different taste. So, if your tank pets don’t like a certain fruit, try something else.

Can I Feed Chocolate To A Goldfish?

Feeding chocolate to any kind of fish is a bad idea. Gold Fishes should be fed pellets and dry fish flakes. It’s easily available in pet stores both online and offline. Chocolate contains harsh toxins along with sugar and fat. That can harm the goldfish’s health.

How Do I Tell If My Fish Doesn’t Like A Treat?

If your pet fish doesn’t like a treat, there are some signs to identify. First of all, the fish won’t eat it. And as it becomes hungry, it will start nudging the aquarium glass to signal you to feed him. Or, it can start digging the aquarium substrates in search of food. Just focus on their behavior, and you will know what they want.


Fish hardly reject any food. Most of the time, they will accept what you let them eat. But that also makes you responsible for their health as an owner. You have to research properly and learn what kind of diet your fish requires.

If you are a beginner, try to stick with the approved fish foods you find in pet stores. If you think the fish needs a change, let them taste some veggies or fruits, as we mentioned earlier. Slowly, you will understand what they like.

As for the chocolate, we think it’s better to eat it yourself than sharing it with your little pets.

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