Choosing suitable fish for your aquarium isn’t easy. Aesthetic factors such as colors, shapes, and sizes need to be taken into account, but the temperaments of your fish are also incredibly important to consider, especially when mixing species to create a diverse, vibrant tank.

Ideally, a tank should include friendly, sociable fish who are easy to adapt to new environments and can live side by side with their tank makes.

But you need to be careful that you don’t house social, peaceful fish with fish that are too aggressive, as they can be bullied or even eaten by their aggressive tank mates. 

If you don’t know where to start with your tank, or just need a little inspiration, we have compiled a list of some of the most popular fish for a 55-gallon tank, and why they are so appealing to aquarists. You will also find suggestions on some optimal combinations. 

Most importantly though, the right temperatures, adequate space to swim and hide, and a functional water filter make for a happy, healthy aquarium.

So you will also find some guidance on what to look for in the essential equipment needed for your 55-gallon tank.

African Cichlids

African Cichlids

Originally found in Lake Tanganyika, Malawi, and Victoria, African Cichlids are tropical fish that are part of the Cichlidae family and include a diverse group of fish.

These include the Livingstonii Cichlid, known for its unique hunting style of playing dead to attract smaller fish and is native to Lake Malawi in the Great Rift Valley region.

Despite what the name suggests, you can also find these fish in Asia and South America.

African Cichlids are common among aquarists because of their different, vibrant colors and unique patterns. For instance, the Livinstonii Cichlids have a spotted coloration, and their prominent dark blotches provide a stunning contrast to silver, yellow, or blue backgrounds.

Meanwhile, the Tropheus Cichlids are perfect additions for a vibrant tank, as they have at least 50 color morphs to choose from. The Auratus Cichlids are very popular among aquarists and highly coveted for their coloration that differs between genders.

The males have a black or dark brown body with yellow or light blue stripes on the upper part of their bodies, while female Auratus Cichlids have a golden yellow body with black and white stripes across the upper parts of their bodies. Their dorsal fins are black and tinged with gold.

Beginner aquarists will naturally make mistakes now and then, but the Cichlids are very forgiving and flexible fish for inexperienced aquarists and can easily adapt to new environments.

Tropheus Cichlids can even develop fascinating social structures that are very satisfying to watch when surrounded by similar tankmates. Cichlids are also excellent feeders – some may even say greedy as they regularly eat more than what they need!

Cichlids are also active swimmers and can follow movements they see outside of the tank. Curious Tropheus Cichlids are also known to line up in the tank if they spot something interesting outside it and take a peek.

These Cichlids in particular have unique and charming personalities and are known to even perform tricks during feeding time. 

The size of the aquarium required for a Cichlid will vary depending on the species you choose. A thirty-gallon tank will be suitable for smaller species and a 50-gallon tank will be suitable for the larger species.

A 55-gallon tank can accommodate 10 middle-sized Cichlids. A good rule of thumb is that the more Cichlids you add to the tank, the larger the aquarium needs to be.

The water in the aquarium should be kept moving, and the ideal temperature should be around 75 to 85 degrees Fahrenheit with a PH level of 7.8 to 8.6.

Things to consider:

Aggressive and very territorial

It is advised that you should not mix African Cichlids with other species as they are very territorial especially when mating and will engage in potentially lethal fights with weaker fish. Auratus Cichlids in particular are known for their aggression.

High waste production

Due to their high waste production a good filtration system is key

Well decorated tank

African Cichlids love to dig, so a well-decorated tank is a must. Choose decor like ocean rocks that provide sturdy structures for the tank and give the fish plenty of crevices to hide in.

For the Livingstonii Cichlid, a well-decorated tank that mimics their natural habit is recommended.

The best substrate for a tank with Livingstonii Cichlids would be Coral sand or Aragonite as it keeps the tank water hard or alkaline. These Cichlids also prefer a darker substrate as it allows them to show off their colors and helps them feel safe.

Meanwhile, rockscapes are crucial for the Auratus Cichlids, especially if your tank is filled with them. This is because the dominant male will use rocks to mark his territory, and the sub-dominant males, female Auratus, and the fry will use these rocks as a hiding spot from the aggressive, dominant male and shelter from him in the crevices.



There are two types of Angelfish. The freshwater Angelfish belong to the Cichlidae family, while marine Angelfish belong to the Pomacanthidae family. Angelfish were originally found in the Amazon River of Brazil. They are named Angelfish due to their fins that resemble wings. 

Angelfish are popular due to their elegant, ornamental form, and their attractive, majestic appearance has earned them the nickname ‘the king of the aquarium’ by some aquarists. These fish are very calm in comparison to the Cichlid and are easy to care for. 

They can live comfortably in aquariums with water temperatures between 78 and 84 degrees Fahrenheit and a PH level of 6.8 and 7.8. Angelfish can also grow quite large so are perfect for a 55-gallon tank. 

Things to consider:

Aggressive towards smaller fish

Despite being relatively calm fish, they can be quite aggressive to smaller fish such as Tetras. However, if you keep a large school of Tetras this should keep them safe from harm.

For example, 12 Neon Tetras can be kept with 4-6 Angelfish in a 55-gallon tank along with aquarium plants and driftwood. Also, 6-8 Angelfish can be kept with a big school of 15-20 ember Tetras too


Gourami are members of the Osphronemidae family and are freshwater fishes. Their native habitats are the slow-moving rivers, swamps, and canals in Asia, and they can be found across the continent in Pakistan, India, and Korea.

Their natural habitat has also allowed them to develop a unique skill. They can breathe on the surface of the water. This is thanks to a labyrinth organ that acts as a lung, because of this they are able to live in shallow, still, and poorly oxygenated water.

A 30-gallon tank is the perfect minimum size for most species of Gourami. But for larger species, such as kissing Gouramis, a 55-gallon tank is more suitable.

They can live comfortably in an aquarium with a PH level of 6.8 to 7.7 and temperatures between 75 to 80 degrees Fahrenheit. 

Gourami are omnivorous and eat tropical flakes, tropical granules, color flakes, and shrimp pellets. Meanwhile, the Kissing Gourami are herbivores and their favorite food is algae rounds. 

Things to consider:

Highly territorial

Gourami are highly territorial so it is advised to keep them in separate tanks from other fish. However, female Gourami tend to be more genial than male Gourami and they can make a good pairing with Angelfish.

Pairing Gourami with Angelfish

As Gourami have similar water specifications and food requirements to Angelfish they can be paired together, and make for a tank that is fairly easy to maintain. A few things to keep in mind though are the age of the fish, aquarium plants, and feeding schedules. 

  1. Choose young fish – When pairing Gourami with Angelfish is it advised to pair young fish with each other. This is because Angelfish can be quite territorial as adults, and are especially caring and protective parents. Therefore, a mixed-age tank may cause problems. Young fish are more likely to adapt to each other, and this may limit territorial behavior as they get older. 
  2. Add aquarium plants – Aquarium plants are not only visually appealing, but they improve oxygen levels, and it helps fish feel safe as it gives them lots of places to hide. Gourami love floating plants as they are an ideal place to attach their bubble nests, while Angelfish prefer tall plants with a large leaf surface to scatter their eggs. 
  3. Coordinate feeding schedules – As both Gourami and Angelfish are omnivorous with similar feeding requirements you can feed them at the same time. Feeding time just got easier! Still, it is advisable to feed each species on opposite ends of the tank. This is because Angelfish can be quite picky feeders and will sometimes take food that’s not meant for them. 


Goldfish are probably the fish you are most familiar with, as they are the most common type of pet fish, and are kept by both beginners and experienced aquarists. Perhaps due to their popularity, they have been bred to produce many varieties over the years in different colors and sizes.

This variation and particularly their bright, shiny colors make them very attractive and appealing to hobbyists and breeders alike. They are widely available at pet stores, are affordable, and have no problem adapting to new environments.

Common Goldfish are among the largest species and require a minimum tank size of 40 to 50 gallons for a pair. But other varieties of Goldfish such as Fancy Goldfish can live alone comfortably in a tank larger than 20-gallons, and pairs can live in a 30-plus gallon tank. A 55-gallon tank can house up to 6 Goldfish.

The ideal temperatures for Goldfish vary between species. For a Common Goldfish, the ideal temperature would be between 66-68 degrees Fahrenheit.

Meanwhile, for a fancy Goldfish, it would be around 65-72 degrees Fahrenheit. The water for a Goldfish tank should always be dechlorinated, but you can also buy aquarium water from a pet store. 

In the wild, Goldfish feed on aquatic plants, crustaceans, insect larvae, fish eggs, and other smaller fish. At home, it is important to feed your Goldfish a healthy, balanced diet. This would include Goldfish pelleted fish food and flaked fish food. 

Things to consider:

Messy and have special water requirements

Because Goldfish have specific water requirements and can be very messy it is advisable to not keep them with other fish. 


Barbs are colorful, hardy, and energetic fish with many different species such as Black Ruby Barb, Denison Barb, Gold Barb, Rosy Barb, Tiger Barb, Tinfoil Barb, and Zebra Barb.

They’re active swimmers and social fish that thrive in small groups of at least 5 other fishes. When considering tank mates, you should consider other active fish that can keep up with the Barbs. 

Depending on the species and size of the Barb, as well as the number of tank mates, they can live comfortably in a 55-gallon tank. They also prefer soft, acidic water that is cool and oxygenated

Things to consider:


Despite being quite sociable, long-finned fish are usually subject to bullying from the Barbs so it is advisable to not pair these together. 

Pair with Rainbowfish

Barbs do pair well with Rainbowfish, however. For example, a school of 6 Tiger Barbs and 6 Rainbowfish will be able to live comfortably together in a 55-gallon tank. Six Rainbowfish and 10 Cherry Barbs will also do well in a 55-gallon tank. 


Tetra is a common name for many small fish from the Characidae family and they were originally found in freshwater bodies in Africa, Central America, and South America.

You can differentiate Tetras from other kinds of small, freshwater fish by their small, adipose fin between the dorsal and caudal fins. You can also differentiate them by their bright colors, particularly the Neon Tetra

What makes the Tetra so appealing is their low-maintenance care, and how sociable they are. They thrive in groups, either with their own kind or different species. 

Tetras are omnivorous and feed on algae, insect larvae, and other small invertebrates that reside in the water. However, at home you can feed your Tetras fresh flake foods. 

Things to consider:

Do not cope well alone

Tetras can become very stressed when alone and this impacts their health greatly.

Pair with discus fish

These sociable fish make good companions for Discus fish. A 55-gallon tank can comfortably accommodate a school of 10-12 Neon Tetras and 6 Discus fish, or 6-8 Diamond Tetras and 6 Discus Fish, or even 6 Discus fish with a school of 30-40 Ember Tetras. However, it’s important to keep any aggressive Tetras away from Discus Fish.

Buyer’s Guide

Now that you have an idea of what fish would thrive in your 55-gallon tank and what the most effective combinations would be, you may also be wondering what equipment you need to run a tank.

There are many different types of equipment on the market that you can add to your aquarium that are mostly optional such as water pumps, UV sterilizers, and automatic fish feeders.

However, sufficient light, a good filtration system, and a water heater are essential to ensuring a safe, comfortable environment for the fish in your aquarium. 


The filter is the most important element of any aquarium and is critical for a safe, healthy tank, as mechanical and biological filtration is what keeps the tank clean. 

Filters come in many varieties, such as HOB, sponge, undergravel, and gravel filters. However, for a 50-55-gallon tank a canister filter is ideal. They not only keep the water clean but are cost-effective when maintaining a large tank.

Whatever filtration system you use, however, it is important not to overload the tank with too many fish as this makes for an unclean, dangerous environment for your aquarium. 


A heater helps to regulate and maintain the ideal temperatures for your tank. It is important to buy a heater that is specifically for a 55-gallon tank to get the best results.

However, sometimes a heater is not needed if, for example, the surrounding environment is already a suitable temperature for your fish, or if your fish require cold water temperatures.


Depending on their native habitats, different species of fish will require different amounts of light. However, if you have aquatic plants in your aquarium then lighting is even more important as the plants rely on different light wavelengths and intensity for photosynthesis. 

Frequently Asked Question

Why use a canister filter for a 55-gallon tank?

A canister filter is ideal for a 55-gallon tank as it can hold more filter media than other filtration systems, and hold larger volumes of water. They also last longer than other filtration systems which mean less money spent on filter maintenance.

They also take up less room in the aquarium compared to other filters. This is because despite being quite powerful they are compact in size.