Tropical fish are a great choice for aquariums. Their bright colors and bold patterns are stunning and they’re a lot of fun to watch.
While you can find tropical fish in both freshwater and saltwater, the one thing they have in common is they like warm water – between 74 to 80 degrees F.
There are a lot of different species of tropical fish from all over the world so finding the best tropical aquarium fish isn’t always easy.
Here are 21 of the most popular ones out there and how to care for them.
Table of Contents
The 21 Best Tropical Aquarium Fish
There are a lot of varieties of tetras but they’re all very colorful and easy to care for which is why they’re so popular.
They’re a schooling fish and should be in groups of at least six. Tetras are middle dwellers and prefer a heavily planted tank with a lot of places to hide.
Tetras are very sensitive to water changes and should be added to a tank after it’s been established. They’re omnivores and prefer a diet that includes brine shrimp and bloodworms.
Because they’re so small, they shouldn’t be housed with large omnivores or aggressive fish.
2. Red Swordtails
Red swordtails are a peaceful fish that are an ideal addition to a community tank but males should be separated because they can get aggressive. These fish are also good jumpers so make sure you keep your aquarium covered.
Red Swordtails are omnivores that will eat fish flakes, bloodworms, and brine shrimp. They’re live-bearing fish that can produce as many as 80 fries at one time.
They’re an easy fish to breed but if that’s not your intention, remove males as soon as possible so they don’t overtake the tank.
3. Dwarf Gouramis
Another peaceful fish that’s great for a community tank is the dwarf gouramis. While they’re not schooling fish, they do like to swim in pairs so getting two of them is a good idea.
They come in a variety of colors including red, blue, and rainbow which have bright orange bodies with blue stripes.
Because of their small size and peaceful nature, dwarf gouramis should not be kept with aggressive fish. They like environments with a lot of plants and places to explore. They’re omnivores and enjoy flake food as well as eating algae.
Guppies are one of the most popular tropical aquarium fish because they’re so easy to take care of and come in just about every color of the rainbow. They’re a good fit for a community tank with other peaceful fish.
They’re omnivores and will eat just about anything though their main diet should be high-quality fish flakes without a lot of filler.
They love school and should be kept in large groups. You can safely house one guppie for every two gallons of water.
5. Rainbow Shark
A good choice, if you’re looking for something really striking, is the rainbow shark. They have bright red fins that really pop against their all black bodies. They start small but can grow to as long as six inches.
While beautiful to look at, rainbow sharks are pretty aggressive with their own kind and shouldn’t be housed with small, peaceful fish. Provide plenty of hiding spaces and keep the fish to water ratio low to avoid any problems.
There are a lot of varieties of pleco but pay close attention to which kind you choose. Common plecos can grow up to 24 inches long and require a tank as large as 150 gallons. Smaller plecos like clowns or dwarfs can live comfortably in a 10-gallon tank.
Plecos are great algae eaters but that shouldn’t be their sole source of food. They’re omnivores and will eat smaller fish if given the chance so keep them happy with pellets and fresh veggies. They’re also nocturnal and will generally hide during the day.
Barbs are a schooling species that should be kept in groups of five or more. There are different kinds of barbs and the come in a wide range of colors.
While they’re not particularly aggressive, they are very active so placid tankmates may need a place to hide.
If you choose a barb, make sure you research the type you’re getting carefully before you buy. Some varieties can get pretty big and require larger tanks but the minimum size for any barb is 20 gallons.
They’re omnivores and like dry flakes as well as small live foods like glass worms.
8. Cory Catfish
If you’re looking for a good fish for a beginner, you can’t go wrong with a cory catfish.
They’re small, hardy, and a great tankmate for non-aggressive fish. They do well in smaller 10-gallon tanks but thrive in larger tanks, too.
Cory catfish are social creatures and like to school in groups of three or more. A single cory will do fine on its own but some are known to be very shy and they’ll be much more fun to watch in a group. They love live plants and need lots of places to explore.
Cichlids are another very diverse group of fish that come in a range of colors and sizes. They’re a popular choice for aquarists because they’re very hearty and add a lot of colors and visual interest to any tank.
These fish are very active and can be very territorial so it’s a good idea to provide a lot of plants, rocks, and other hiding places for their tankmates.
They like to hunt for food and have been known to dig into the substrate looking for something to eat.
10. Otocinclus Catfish
Ottos are a good fish for an experienced aquarist. They do best in a tank that’s already established and are a little sensitive to their environment. These fish are scavengers that are small and very fast making them fun to watch.
These fish prefer heavily planted tanks and like a lot of algae for them to eat. They’re non-aggressive and don’t have any way of defending themselves so housing them with aggressive fish isn’t a good idea unless they have a lot of places to hide.
Bettas are a pretty easy fish to keep it’s pretty common knowledge that they’re aggressive. Male bettas should never be placed in the tank together although large groups of females can generally co-exist peacefully.
If your tank is large enough and there are plenty of places to hide, it is possible to keep a betta with non-aggressive bottom-dwelling fish.
They require a lot of protein to thrive so store-bought betta pellets are the best choice for food.
12. Black Ghost Knifefish
This is one meant only for experienced aquarists and is a really unique addition to a tropical tank.
Black Ghost Knifefish are one of the most unique looking species around. They have no abdominal or dorsal fins and a long, wavy fin that runs along their ventral side.
The biggest thing to note about these fish is they don’t have scales. This is really important because it means they’re more prone to the effects of changes in water chemistry as well as bacteria and chemicals in the tank.
A UV sterilizer light is recommended as it can decrease the chance of disease.
There are a few varieties of mollies. Most of them are bright oranges and reds which adds a nice pop of color to your tank.
Mollies are livebearers which means they don’t lay eggs. They’re also really easy to breed in an aquarium setting.
Mollies are a popular beginner fish because they’re pretty tolerant of water variations. They prefer an environment with a lot of strong plants, rocks, and caves to explore. They’re omnivores who eat just about anything you give them.
Angelfish are so popular because of their interesting shape and gorgeous colors. They’re a good choice for someone with a bit of experience because they require tanks that are pretty large. If you want to keep a few, you’ll need a 50-gallon tank.
Community tanks are generally not a good idea for angelfish unless they’re done very carefully. These fish are aggressive toward smaller fish who like to nip at their fins.
With proper care, angelfish can grow to about 6-inches long and live up to 15 years.
A fun fish that’s easy to care for, loaches are a great addition to a community tank.
They’re bottom dwellers who enjoy schooling and can actually get very lonely if they don’t have other loaches around.
These peaceful bottom dwellers spend their time rooting around the plants and rocks at the bottom of the tank.
Some stay at about three inches long but other species grow to about 12 inches so make sure you have the right sized tank to accommodate them.
Clownfish are a good choice if you have a saltwater reef tank. They’re popular because of their bold orange, black, and white coloring and because they’re pretty easy to take care of.
A single clownfish doesn’t require a lot of space and will happy in a well-maintained 10-gallon tank.
Multiple clownfish kept in the same environment can be aggressive with one another. The best way to avoid this is to introduce them at the same time and give them plenty of space.
They do great with other fish species that are about the same time but shouldn’t be kept with large carnivores.
Platys are a small, colorful fish that fun to keep and easy to breed. They’re a good beginner fish for a community tank because they’re hardy enough to tolerate some stress and are friendly and non-aggressive with other fish varieties.
These fish breed quickly and should be kept with an even number of males to females or up to two females for each male.
Typically, males only get aggressive with other males when they’re trying to mate. They’ll eat just about anything and even like nibbling on small bits of boiled vegetables.
18. Harlequin Rasbora
Another great addition to a community tank is the Harlequin Rasbora. These are schooling fish that should be kept in groups of eight to ten.
They have an orange-red body with a black wedge by their tail and are look quite impressive when swimming in a group.
These freshwater fish will eat just about anything, including flakes, frozen, and live foods. Some good tankmates for Harlequin Rasbora are tetras, dwarf gouramis, bettas, danios, and cory catfish.
19. Threadfin Rainbow Fish
Threadfin Rainbow Fish are a great schooling fish that come in beautiful reds, greens, and blues and their long fins add interesting detail. These fish are happiest in schools of six or more and love to hang out in the top or middle of the tank.
These are a good fish for a beginner because they’re generally easy to care for and only require a 10-gallon tank.
Males can sometimes be aggressive with each other but if they’re kept in larger groups with several females, this isn’t usually a problem.
20. Tropical Discus
This is another great choice for someone with a bit of experience with fishkeeping because the Tropical Discus does require a lot of care.
They’re colorful, graceful, and fun to watch and require a larger tank. A general rule of thumb is one discus per 10 gallons.
Because they’re so sensitive to pH levels and ammonia, housing them with a lot of live plants is a good idea.
They’ll eat a variety of foods but are primarily carnivores so make sure you provide them with plenty of bloodworms and high-quality pellets.
21. Orange Butterflyfish
There are a few types of butterflyfish but the Orange Butterflyfish is the best choice for a beginner and does pretty well in a community tank. It’s a hearty variety that’s peaceful and its bright colors and patterns are stunning.
These fish are meant for large tanks of 120 gallons or more. They love a lot of open space to swim as well as rocks and plants to hide in.
Feeding should be done three times a day and they love meaty items like shrimp and frozen marine preparations.
How to Set up an Aquarium for Tropical Fish?
The first step to setting up a tropical fish tank is planning. Here are some of the main things to consider.
● Where are you going to set up your aquarium?
The best place for an aquarium is a hard, flat surface. Small tanks of 30 gallons are less can be placed on a sturdy countertop or table but larger tanks require a proper cabinet or supporting structure.
You should also make sure the ground is even. Slanted floors cause uneven pressure against the glass walls of the aquarium which can cause damage over time.
Finally, choose a spot close to an electrical outlet since you’ll need to power lights, the filter, and heaters. Avoid extension cords if possible to keep the wires at a minimum.
● What kind of fish are you planning to keep?
This is important because every species of fish has its own space requirement. Buying a 10-gallon tank and then expecting to fill it with species that require a lot more space is unfair to the fish.
● Do you have everything you need?
Before you get started, make sure you have what you need to put together a proper setup.
Once you have everything planned out and all of your supplies ready, follow these basic steps to set up your aquarium.
1. Wash the substrate. One method is to empty it into a large bucket and fill using high-pressure water. Agitate it with your hands, dump out the water, and repeat a few more times until the wastewater runs clear.
2. Add the substrate to the bottom of the tank. Use a shovel, small bucket, or scoop to gently place it on the bottom to prevent any damage.
3. Fill up the tank. This step varies depending on whether you’re using freshwater or saltwater. Freshwater is much easier to maintain. All you need to do is use a water de-chlorinator after filling and with each water change.
The easiest way to set up a saltwater tank is to buy premixed saltwater. If you do choose to mix it yourself, make sure you buy proper sea salt mix from the pet store. Do not use table salt.
If you choose to use tap water, make sure it’s properly treated. Fill the aquarium about ⅓ of the way then test the water.
4. Rinse the filter media. Set up the filter and place the media inside. Hang-on filters require you to fill them with water to start cycling. At this point, make sure the filter is cycling at the maximum rate.
5. Set up the heater. Small aquariums only need one but larger tanks require two. Choose a model that fits comfortably inside your tank without taking up too much open space.
Stick the heater where there is good water flow and set it between 74 and 80 degrees.
6. Choose an appropriate light. Using one with a timer is ideal as the light should really only be on about eight hours a day or so.
7. Cycle your tank. This is the most important part of setting up a new tank.
Cycling allows the necessary beneficial bacteria to grow. Once you add fish, waste builds up and releases ammonia, which is toxic. Beneficial bacteria converts ammonia to a non-toxic form.
Having a stable bacterial colony in place before adding any fish helps get things started off on the right foot. Waste will be dealt with right away because the tank will already be equipped to handle it.
Some people cycle their tank using a few fish to introduce ammonia to the tank to encourage bacterial growth. This can be considered cruel since these fish are going to go through a lot of stress initially. Adding a few drops of ammonia every day is a safer, cruelty-free way to proceed.
Cycling can take anywhere from two to eight weeks. The water should be tested after two weeks and every week or so after until you’ve seen the nitrite levels spike and fall back to zero. Then, you’re ready to add fish.
8. Add fish slowly. Start with hardier species and add new varieties one at a time, testing the water to make sure the nitrite levels have returned to zero after each new addition. This is a sign that the bacteria are keeping up with the current load and are ready for more.
How to Take Care of Tropical Fish Aquarium?
Now that you have your tank set up and stocked with fish, it’s important to perform proper care and maintenance.
1. Feed your fish regularly. Until your tank is well established you should feed your fish once a day. As time goes on, you can give them smaller amounts throughout the day.
There are special considerations for saltwater fish that are wild caught. Because they’re not used to eating aquarium food, they should be slowly acclimated to it over a few weeks.
Food is the main source of waste in your tank so be very careful not to overfeed. Not only does the water get dirty faster but too much food is harmful to your fish.
The standard rule is to give your fish only what they can consume in three to five minutes. If there’s any food left, you’re overfeeding.
2. Keep a close eye on the temperature. Tropical fish require a temperature between 74 and 82 degrees F. Most heaters automatically maintain the ideal temperature but it’s a good idea to get in the habit of checking.
3. Test the water every week. There are a lot of different testing kits you can use right at home or you can take a sample to your local pet store and have them test it for you.
Specifically, you should be looking for pH, ammonia, nitrates, nitrites, and chlorine levels for freshwater.
Saltwater tanks have more specific requirements and require special testing kits. Some saltwater fish also have special requirements you might have to check for.
If any levels are elevated, the easiest way to correct it is to remove and replace some of the water until everything is closer to where it should be.
4. Replace water regularly. For freshwater tanks, 10% of the water should be removed and replaced every week and once a month, 25% of the water should be removed and replaced. Make sure that the water is the same temperature so as not to shock your fish.
Saltwater tanks are a bit different. Remove 20% of the water once a month or 5% every week and replace with prepared salt water.
5. Clean the tank weekly. Every week you should clean the inside walls to clear away any algae. Make sure you use the right scrubber, especially if you have an acrylic tank that can be easily scratched.
6. Check the filter every month. Rinse the filter floss in discarded tank water and replace the carbon and other disposable media. Make sure the pump is working appropriately, too, and that the intake isn’t blocked with anything.
7. Take care of plant life. Dead leaves and plants can throw off the water balance by adding more debris and ammonia. Make sure you tend to them regularly and remove any brown or dying leaves.
The best tropical fish for aquarium is the one that suits you best. There are so many to choose from of all different sizes, shapes, and colors that it’s impossible to say that one is better than the other.
That said, make sure you choose one that is compatible with your level of experience that you’re willing and able to care for properly. Keeping a healthy aquarium does take a little bit of work but the payoff is definitely worth it.