Ultimate Guide : Fish for 55 gallon tank


The allure of a 55-gallon tank entices both novice and veteran aquarists. With its substantial capacity, this medium-sized aquarium provides a black slate for crafting fascinating aquatic ecosystems brimming with life. In this guide, we’ll delve into the gradations of tank capacity, fish size, temperament, compatibility, aquascaping, and water quality to help you make informed choices for your 55-gallon aquarium.


Understanding Tank Capacity and Fish Size

The “Inch per Gallon” Principle

One of the first things to ponder when choosing fish for your 55-gallon tank is the “inch per gallon” rule. Traditionally, this rule states that you can have one inch of fish per gallon of water. However, in larger tanks like the 55-gallon, this principle becomes more nuanced. A 55-gallon tank can indeed accommodate more fish, but that doesn’t mean you should go overboard.


Foresight for Growing Fish

Some fish species may start small but eventually develop over time. This is particularly true for certain cichlids and catfish. When choosing these species, it’s crucial to consider their potential size when they reach adulthood. Failure to plan for this can result in congestion, territorial clashes, and declining water quality.

Best Fish Options for a 55-gallon Tank


Silver Dollar Fish

Appearance: Silver Dollar Fish are named for their round, flat bodies that look like silver coins. They add a distinctive and captivating depth to your tank.

Temperament: These fish are generally peaceful and thrive in schools. They are best kept with their kind or other non-aggressive tank mates.

Diet: Silver Dollar Fish are omnivores, and their diet should include a variety of foods like pellets, flake food, and vegetables.

Care Level: Considered intermediate due to their precise dietary needs and sensitivity to water conditions.

Note: Silver Dollar Fish are known to munch on plants, so choose your aquarium flora accordingly.


Bala Sharks

Appearance: Despite their name, Bala Sharks are not true sharks but are named for their appearance. They have sleek silver bodies with black margins on their fins.

Temperament: Bala Sharks are generally peaceful but are extremely energetic swimmers. They require ample space to roam.

Diet: These omnivores enjoy a diet of pellets, live food, and vegetables.

Care Level: Need interim care because of their active nature and dietary requirements.

Note: Bala Sharks are social creatures, so keeping them in groups is recommended for their well-being.

Firemouth Cichlid

Appearance: Firemouth Cichlids are named for their striking appearance, characterized by a bright blue body with fiery red throat and belly markings.

Temperament: They can be territorial but can coexist with similar-sized fish when provided with enough hiding spots and territories.

Diet: Firemouth Cichlids are omnivores and should be fed a balanced diet of pellets, live food, and flake food.

Care Level: Moderate care is required thanks to their territorial nature.

Note: Adequate hiding spots and territories are crucial to managing their territorial behaviour.

Plecostomus (Common Pleco)

Appearance: Plecostomus, commonly known as Plecos, are sucker-mouthed catfish with armoured plates covering their bodies.

Temperament: They are generally peaceful, making them suitable for community tanks.

Diet: Plecos are herbivores and feed on algae wafers, vegetables, and occasional live food.

Care Level: These fish are easy to intermediate in terms of care.

Note: Plecos can grow quite large, so ensure your tank has enough space for their growth.

Tiger Barbs

Appearance: Tiger Barbs are instantly recognizable with their bright orange bodies adorned with distinctive black stripes.

Temperament: They are active fish but can be fin-nippers if not kept in a large enough school.

Diet: Tiger Barbs are omnivores and enjoy a diet of flake food, live food, and pellets.

Care Level: Easy to care for and suitable for novices.

Note: To minimize aggressive behaviour, it’s best to keep them in schools of six or more.

Navigating Fish Temperament and Compatibility in Larger Tanks

In a 55-gallon tank, you can create diverse and harmonious aquatic communities. Understanding fish temperament and compatibility is vital to prevent conflicts in your tank. Some fish are more territorial, while others are docile. Mixing these temperaments can be challenging but also rewarding.

Dynamics of Community Tanks:

In larger setups like a 55-gallon tank, you have the canvas to create a diverse aquatic community. It’s like orchestrating a symphony of several personalities, and believe me, it can be a satisfying experience. However, it’s crucial to understand the dynamics at play.

Mixing Fish of Different Temperaments:

Comprehend their temperament, ideal water conditions, and fish-to-fish compatibility. It’s like getting to know your neighbours before relocating to a new neighbourhood.

  • Peaceful Fish: 

These are your “good neighbours” in the tank. They commonly get along with others and cause the least trouble. Fish like Silver Dollar Fish and Common Plecos fall into this category.

  • Semi-Aggressive Fish: 

These fish can be a bit more competitive but can cohabit with the right tank mates. Firemouth Cichlids are a classic example. To mix them successfully, create hiding spots and areas using rocks and plants.

  • Aggressive Fish: 

Some fish are just naturally spunky, like Tiger Barbs. My intuition here is to keep these fish in larger schools (six or more) to disperse their aggression. This mirrors their natural behaviour in the wild and reduces fin-nipping.

  • Bottom Dwellers: 

Don’t forget about the fish that dwell near the substrate, like Bala Sharks and Plecos. They need their space too. Provide hiding spots among decorations and plants to keep them comfortable.

3. Structures and Plants for Managing Territory Disputes:

Now, let’s talk about the practical solutions for keeping the peace in your larger tank. Structures and plants play a vital role in managing territory disputes.

  • Rocks and Caves: 

Use rocks and caves strategically to construct separate boundaries. As a result, fish don’t infringe on one another’s space. It’s like designing different rooms in your house for family members.

  • Plants: 

Live plants not only add beauty but also serve as natural barriers. They create walls that help reduce aggressive behaviour. Consider adding dense plantings in areas where territorial disputes tend to occur.

  • Floating Plants: 

These act as underwater worlds with verdant canopies. They provide shade, security, and hiding spots for fish. Floating plants can be especially useful if your fish favours the top tiers of the tank.

Amplifying the Beauty of a 55-gallon Tank with Plants and Décor

When it comes to setting up a 55-gallon tank, one of the most exciting aspects is the opportunity for creative aquascaping. It’s just like a watercolour waiting to be painted into a mesmerizing underwater world.

Choosing the Right Plants:

Now, when it comes to plants, not all of them are suited for larger tanks. I heartily endorse Vallisneria and Cryptocoryne as two excellent choices for your 55-gallon beauty.

  • Vallisneria:

 This plant adds grace and movement to your tank. Its long, ribbon-like leaves wave softly in the water, creating a dynamic visual effect. It also acts as a natural home for fish and provides oxygen, contributing to a healthier tank ecosystem.

  • Cryptocoryne:
  •  These plants bring depth and texture to your aquascape. Their broad, wavy leaves come in various shades of green and brown, adding a touch of elegance. Cryptocoryne also provides hiding spots for fish, making them feel secure.

The Magic of Rocks, Driftwood, and Caves:

Now, let’s discuss the hardscape elements – rocks, driftwood, and caves. These aren’t just decorative; they play essential roles in your tank’s ecosystem. I’ve found that strategically placing these elements can truly elevate the visual appeal of your 55-gallon tank.

Rocks, like lava rocks or aquarium-safe stones, serve as anchors for your plants and create intriguing underwater vistas. Stack them in various formations, leaving open spaces for fish to swim through, and you’ll have a dynamic and visually engaging aquascape.

Driftwood adds a touch of natural beauty and provides hiding spots for your fish. It can be a central focal point or integrated into the background. Be sure to choose driftwood that won’t alter your water chemistry too much.

Caves, often created with rocks or specially designed aquarium ornaments, offer shelter and security to your fish. These hiding spots can be vital, especially if you have species that appreciate a bit of privacy or territorial boundaries.

The key to successful aquascaping in a 55-gallon tank is balance. Create a harmonious blend of plants, rocks, driftwood, and caves to ensure both aesthetic appeal and the well-being of your aquatic inhabitants.

Preserving Water Quality in a 55-gallon tank

One advantage of a larger tank is that it generally offers greater stability in terms of water parameters. However, maintaining good water quality is still paramount. Here are some key points to keep in mind:

  • Regular Water Changes: Perform regular water changes to remove accumulated waste and maintain stable water parameters.
  • Water Testing: Invest in water testing kits to monitor parameters such as pH, ammonia, nitrites, and nitrates. Regular testing helps you catch and address issues early.
  • Efficient Filtration: Choose a filtration system that suits the needs of a 55-gallon tank. Canister filters or hang-on-back filters are popular choices, providing efficient mechanical and biological filtration.


In conclusion, a 55-gallon tank is a fantastic choice for aquarists who want to explore the vast possibilities of aquatic life. The diversity of fish species, the creative potential of aquascaping, and the relative ease of maintaining water quality make it an attractive option for both beginners and experienced hobbyists.

As you embark on your 55-gallon journey, remember to continually educate yourself about the specific needs of your chosen fish species and adapt your tank accordingly. Share your experiences, challenges, and triumphs with fellow aquarists, and let the beauty of your 55-gallon tank inspire others to join this captivating hobby.