December 22

8 Sea Creatures You Shouldn’t Put In Your Aquarium


Fishes and other sea creatures are sometimes taken to households as pets. They are much more quiet, adorable, and can be easily taken care of. There are a variety of species that you can put in an aquarium.

According to Adam of, these are the best fishes to put in your fish tank and they are convenient to own.

As much as we want to help, adopt, and take care of sea creatures as pets, there are certain species that should not be kept in a fish tank.

It seems that all animals that live in the sea can be taken as pets; however, some of them are not suitable for one due to their behavior and characteristics. Beautiful they might seem, there are certain risks when you put them into your aquarium.

Nevertheless, let us proceed in identifying these 8 sea creatures that you should not put in your fish tank.

1. Fire Bellied Toads

These frogs are native to the country of South Africa. The appearance of this species is obvious by their name. It is derived from the brightly colored patterns of red- or yellow-and-black on the toad’s body.

However, even if it is named as a toad, it is still categorized as a frog due to its characteristics of it. These unique-looking amphibians are poisonous as the skin of this frog secretes toxins.

The color red in their body serves as a warning as their skin is poisonous and even humans are warned to not touch them. While they do not impose great danger to other animals as long as they do not touch or bite this frog, it can contaminate the water with poison when added to the aquarium.

It will be a lot of work in replacing your water day by day just to secure the safety of other animals with the Fire Bellied Toad.

2. Angelfish

This fish is commonly seen in your local pet stores for sale. They are native to the tropical freshwaters of South America and can grow up to a length of 10-12 inches long in the wild. Additionally, when taken in captivity as pets, they are easy to take care of and do not require high maintenance.

However, when Angelfish grow to adulthood it becomes aggressive. This might become a problem to your aquarium, especially if you have a community in your fish tank. Furthermore, when the time of pairing comes, these fishes will be aggressive to one another.

3. Freshwater Crayfish

These sea creatures are crustaceans that look like small lobsters. Freshwater crayfish can be easily kept in your house aquarium. However, it is not ideal for community aquariums as it can be aggressive at certain times.

There are a lot of species of freshwater crayfish that have different aggressiveness, so you better watch out if you are planning to take care of one or more.

Additionally, they are messy eaters. Thus, it requires the owner to change the water regularly to ensure its quality of it. There are specific water measurements to meet when you are considering them as pets.

4. Gouramis

These fishes are often selected by pet owners as they are beautiful and adorable to have as pets. They are native to the continent of Asia and can group medium to large-sized fish.

However, despite their small appearance, they can eat other fishes that are small enough to fit in their mouths. They are also aggressive and would bully other fishes that can kill them. They are also great together with Angelfish as they possess almost the same characteristics.

    5. Oscar

    These fishes are cute and beautiful due to their size and colors. They are native to the c and can grow up to 18 inches in length. When taking care of these fishes, you will need a bigger aquarium and to observe their behavior regularly.

    These fishes are very aggressive as they claim an area in the aquarium as their own and would inflict harm to other fishes that are in your fish tank. Furthermore, they are omnivores that would also eat smaller fish and would also bite you.

    6. Guppy

    These fishes are good to consider as a pet. They are also known as million fish or rainbow fish and are also the most widely distributed tropical fish in the world.

    They are considered as good beginner fishes and to be in community aquariums; however, they can have parasites and worms in their body. While they have these parasites on their body, this might cause the fish to die and other fishes might be infected with the same parasite causing an infestation.

    7. Large Plecos

    Plecos are fishes that are rare to find and expensive to buy. They possess beautiful colors and are very appealing if you want a pet that is adorable.

    But, as it stays in your fish tanks, it gets so big and would become very aggressive to other fishes in your aquarium. But not all plecos are not suitable for your aquarium like Bristlenose Pleco.

    8. Goldfish

    Yes! You read it right. Goldfish should never be put in bowls or aquariums that are unfiltered. These fishes are the most considered as beginner fish.

    However, these fishes require a lot of oxygen and if you are just starting in this hobby of aquariums, then it is not the best fish for you. It can also grow to a large one and would require a bigger fish tank for it.

    Furthermore, it generates a lot of waste which can be harmful to themselves if it accumulates in the provided fish tank.


    There are certain sea creatures that we are often deceived by their looks and the concepts of the community. It is important to know every single detail about the fish or other sea organisms you would like to take as a pet.

    By collecting the needed information about them, you might eradicate the possible problems that might occur and terminate the risk of harming you and the other fishes you are putting inside your aquarium.


    Some other articles you might find of interest:

    Learn more about these sought-after fish breed this 2021:

    Betta Fish – What Are They And Whether Should You Get One

    Are you looking for freshwater aquarium ideas?

    25 Best Freshwater Aquarium Fish For Beginners in 2021

    Match your aquarium and freshwater fishes here:

    Colorful Freshwater Fishes for Your Aquarium – Appearance, Behavior, and Compatibility


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