How to Choose Cold Water Fish, Tropical Fish or Marine Fish

Faced with so many different fish, where do you start?  Go to the local aquarium store and you will undoubtedly find out what fish to keep.  Pet fish are usually rich in colors, special shapes, or full of personalities, and they almost wink at you and say, “Buy me, buy me!”

Not all fish can happily stay in the same aquarium.  Some large fish may harm small fish; some fish will eat other types of fish.  Marine fish must be kept in marine aquariums filled with artificial seawater.

Your taste, purpose, budget, and ability to keep fish will affect what kind of fish you buy. Goldfish is cheap and easy to buy, and it does not take up too much time to keep. The price of clownfish is more expensive, the requirements for aquarium equipment are higher, and the maintenance is more complicated. The difficulty and cost of keeping tropical fish are between goldfish and clownfish.


The key at this stage is to stay calm.  Before you buy any fish, you need to understand the needs of the fish you want to buy. A good retailer should also ask how well you know the fish before he sells any fish to you and give you any suggestions on choosing a suitable aquarium.

Choose tropical fish, cold water fish, or saltwater fish

These three types of fish cannot be mixed together. This will be the first major decision you have to make when you start fishkeeping. As mentioned before, these three types of fish have different breeding costs and maintenance techniques and require different breeding equipment and even different types of aquariums.

Cold water fish

Cold water fish usually refers to goldfish or other pet fish that do not need warm water to survive. They are easy to raise and have a long lifespan. Since goldfish can grow to 30 cm or larger, they need a spacious aquarium. The number of goldfish species is not too much, but there are many varieties of each species.

What do you need to know about cold-water fish?

Since goldfish will grow larger and eat more, they will produce a lot of pollutants, which means you need to prepare a corresponding filtration system to treat the pollutants in the water. Goldfish are generally docile and will not fight with other fish, but Ryukine may be attacked by other fish.  Although people always like to keep goldfish in a bowl-shaped container, a medium or large aquarium is the most appropriate container for raising goldfish.

How to choose cold water fish

Tropical Fish

Tropical fish are rich in colors, shapes, and types, and there are thousands of species to choose from. These fish vary in size, cost, and maintenance. Because of their various species, they have become the most popular type of pet fish. Even if you only have a small aquarium, there will be tropical fish species that suit you, and there are many tropical fish that are no more difficult to raise than goldfish.

Tropical fish can be placed in aquariums with different styles, such as aquatic plants, original ecological aquariums with cichlids, and South American-style aquariums with discus. In some cases, some tropical fish can be as good as marine fish in terms of color, cost, and the skills required to raise them.

What do you need to know about tropical freshwater fish?

Unless you live in a tropical area, the aquarium for tropical fish needs to be heated, so your budget must include an aquarium heater and the cost of running it. There are so many fish species to choose from, not all fish species can coexist harmoniously, so you have to understand the habits of different species of fish in advance.

Marine fish

Marine fish have the most vivid colors and the most peculiar shapes. Due to the place of origin, these marine aquarium fish live in tropical oceans and have very demanding environmental requirements. They are considered to be the most difficult type of fish of three types of aquarium fish. They take up the most time of the fish keeper, use the best equipment, and are generally considered unsuitable for beginners.

The positive side is the uniqueness of seawater aquarium fish, and while raising these seawater aquarium fish, you can also raise live corals and many coral reef creatures.

What do you need to know about saltwater aquarium fish?

Due to the need to prepare artificial seawater, it takes longer to change the water in the aquarium. In addition, although there are several thousands of species of fish that can survive on coral reefs, only some fish can be cultured in seawater aquariums, and most require sufficient space. Nano aquariums are also feasible, which can create a small ecological environment and a more economical coral reef environment.

So you have to spend some time thinking before keeping fish, and then determine the species of pet fish that suit you. For your reference, The following table summarizes the major conditions required for keeping three aquarium fish.

  Cold Water Fish Tropical Fish Marine Fish
Fish Species A few Many Many
Difficulty to Keep * ** ***
Cost to Set up Low Medium High
Cost to Maintain Low Medium High


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