Want big freshwater fish for your home aquarium? Many large fish like Oscars, Bala Sharks, and Plecos grow 6–24 inches and make amazing pets. They bring bold personality, movement, and color to your tank. These fish need large tanks, strong filtration, and peaceful tank mates. In return, they offer years of beauty and interaction.
In this guide, you’ll find 11 of the best large freshwater fish from calm bottom dwellers to bold swimmers organized by size. For each species, we include size, tank needs, behavior, and why they make great pets.
What Counts as a ‘Large’ Freshwater Fish?
In aquariums, a “large” fish is usually over 6 inches long. They’re not pond-sized, but they need more space than guppies or tetras.
Common Traits:
- Size: 6 to 24 inches
- Tank Size: Most need 55 gallons or more
- Behavior: Active, curious, sometimes territorial
- Care: Moderate to advanced
- Filtration: Stronger systems needed due to waste
With the right setup, large freshwater fish become impressive, long-lived pets.
1. Silver Arowana (Osteoglossum bicirrhosum)
- Size: Up to 24 inches
- Lifespan: 10–15 years
- Tank Size: 250+ gallons
- Temperament: Semi-aggressive, predator
Silver Arowanas are prized for their sleek, dragon-like appearance and powerful swimming. They jump, so you need a tight lid. Best kept solo or with other large, calm fish.
Why It’s Great:
- Massive size and elegant swimming
- Long lifespan
- Stunning silver shine under light
Pro Tip: Needs a very secure lid—they can leap several feet.
2. Common Pleco (Hypostomus plecostomus)
- Size: Up to 18 inches
- Lifespan: 10–15 years
- Tank Size: 75+ gallons
- Temperament: Peaceful, bottom-dweller
Common Plecos are large, armored catfish that are well-known for their algae-eating habits. However, they can’t survive on algae alone. They require a diet of sinking pellets, fresh vegetables, and plenty of hiding spaces like driftwood or caves. These nocturnal bottom dwellers are hardy and long-lived, often growing much larger than expected. While peaceful, they may become territorial with other bottom fish if the tank is too small or lacks cover.
Why It’s Great:
- Hardy and long-lived
- Helps control algae
- Unique look and behavior
Pro Tip: Feed sinking pellets and vegetables—not just algae.
3. Tinfoil Barb (Barbonymus schwanenfeldii)
- Size: Up to 14 inches
- Lifespan: 8–10 years
- Tank Size: 125+ gallons
- Temperament: Peaceful but very active
Tinfoil Barbs are large, shimmering silver fish known for their active swimming and peaceful nature. They can grow quickly and need a spacious tank with open swimming areas. These fish feel most secure in groups of five or more, which also reduces stress and encourages natural schooling behavior. Their constant movement and reflective bodies make them a lively and eye-catching addition to large freshwater tanks, especially when housed with similarly sized, non-aggressive species.
Why It’s Great:
- Fast and fun to watch
- Schooling adds energy to tanks
- Peaceful with big fish
Pro Tip: Keep in schools of 5+ to reduce stress.
4. Bala Shark (Balantiocheilos melanopterus)
- Size: 10–12 inches
- Lifespan: 8–10 years
- Tank Size: 125 gallons
- Temperament: Peaceful, active, skittish
Despite their name, Bala Sharks are not aggressive at all. These sleek, silver-bodied fish are peaceful and very active swimmers. They prefer to live in schools and are happiest when kept in groups of at least three to five. Bala Sharks thrive in spacious tanks with plenty of room to dart around. Their elegant appearance and constant motion make them a beautiful and energetic addition to any large freshwater aquarium setup.
Why It’s Great:
- Elegant appearance
- Great community fish if tank is big enough
- Adds constant motion
Pro Tip: Jumpers! Use a lid.
5. Bichir (Polypterus senegalus)
- Size: 10–12 inches
- Lifespan: 10+ years
- Tank Size: 75+ gallons
- Temperament: Calm, predatory
Bichirs are ancient-looking fish with long, armored bodies and a unique way of moving—more crawling than swimming. They are mostly active at night and prefer staying close to the bottom. While peaceful with larger fish, they are predators by nature and will eat anything small enough to fit in their mouths. These fascinating fish bring a prehistoric feel to the aquarium and thrive best with tank mates too large to be considered food.
Why It’s Great:
- Prehistoric look
- Active at night
- Peaceful with the right tank mates
Pro Tip: Leave space at the surface—they breathe air.
Explore more in our Freshwater Fish Guide.
6. Oscar Fish (Astronotus ocellatus)
- Size: Up to 12 inches
- Lifespan: 10–15 years
- Tank Size: 75+ gallons
- Temperament: Smart, territorial
Oscars are highly intelligent fish that recognize their owners, often coming to the front of the tank to greet them or beg for food. They form real bonds and display curious behavior, making them one of the most interactive freshwater species. However, they need plenty of space and careful tank mate selection, as they can be territorial and will eat smaller fish. Their personality makes them a rewarding choice for dedicated aquarists.
Why It’s Great:
- Highly interactive
- Great solo or species-only tanks
- Striking color varieties
Pro Tip: Don’t mix with small fish—they’re likely snacks.
7. Severum Cichlid (Heros severus)
- Size: 8–10 inches
- Lifespan: 5–10 years
- Tank Size: 55+ gallons
- Temperament: Calm, semi-territorial
Severum Cichlids are gentle giants compared to many other cichlids, making them a solid choice for aquarists who want color without aggression. These fish grow large but stay calm in community setups when given enough space and hiding spots. Their peaceful nature, round body, and flowing fins add grace to any tank. With proper care, they display stunning coloration and are easy to pair with other mid-sized, peaceful tank mates.
Why It’s Great:
- Colorful and elegant
- Works in community tanks with space
- Can be kept in pairs
Pro Tip: Use sturdy plants—they sometimes nibble.
8. Jack Dempsey Cichlid (Rocio octofasciata)
- Size: 8–10 inches
- Lifespan: 8–10 years
- Tank Size: 55 gallons
- Temperament: Semi-aggressive
Named after the legendary boxer, the Jack Dempsey Cichlid is bold, both in its appearance and behavior. Its body shimmers with metallic blues and greens, often catching the eye of anyone nearby. Known for its strong territorial instincts, it thrives in a tank with proper space and hiding spots. This fish is best suited for experienced aquarists who enjoy a confident, interactive fish with a unique personality and stunning coloration.
Why It’s Great:
- Iridescent blue/green body
- Strong personality
- Great for experienced keepers
Pro Tip: Add caves and space to reduce aggression.
9. Firemouth Cichlid (Thorichthys meeki)
- Size: 6–7 inches
- Lifespan: 8–10 years
- Tank Size: 40–55 gallons
- Temperament: Semi-aggressive when spawning
Firemouths are known for flaring their bright red throats when they feel threatened or challenged. Outside of those moments, they’re calm and easy to care for, especially when given enough space and proper tank mates. They adapt well to community tanks and can thrive with similarly sized fish in well-structured environments. Their personality and color make them a favorite among cichlid keepers.
Why It’s Great:
- Bright colors
- Easy to care for
- Good with similarly sized tank mates
Pro Tip: Give hiding spots to reduce tension.
10. Electric Blue Acara (Andinoacara pulcher)
- Size: 6–7 inches
- Lifespan: 8–10 years
- Tank Size: 55 gallons
- Temperament: Peaceful and smart
Electric Blue Acaras are peaceful cichlids with bright, glowing blue scales that stand out in any tank. They’re easy to care for, friendly with many fish, and perfect for planted tanks. Their calm nature makes them ideal for beginners and experienced hobbyists alike. These fish stay active, show personality, and add vibrant color without causing trouble, making them one of the best large fish for peaceful freshwater aquariums.
Why It’s Great:
- Peaceful and colorful
- Low aggression
Ideal for planted aquariums
Pro Tip: Matches well with Rainbowfish and Corydoras.
11. Rainbow Cichlid (Herotilapia multispinosa)
- Size: 5–6 inches
- Lifespan: 8–10 years
- Tank Size: 40 gallons
- Temperament: Peaceful
Rainbow Cichlids are one of the best beginner-friendly cichlids you can keep. They’re small for a cichlid, easy to care for, and surprisingly colorful—changing shades under different lighting. Unlike many others in their family, they don’t dig or destroy live plants. These fish are peaceful, adaptable, and can thrive in planted or community setups with other calm species. Their calm personality and hardiness make them perfect for new aquarists.
Why It’s Great:
- Beginner-friendly
- Color shifts in good lighting
- Compatible with many peaceful fish
Pro Tip: Perfect for planted or low-aggression tanks.
Tips for Keeping Large Freshwater Fish
Tank Size
- Most need 55 to 250+ gallons
- Long tanks are better than tall ones
Water Quality
- Strong filtration is a must
- Clean weekly, change 25–40% water
Feeding
- Feed a mix of pellets, frozen, and fresh foods
- Avoid overfeeding to keep water clean
Tank Mates
- Pick fish with similar size and behavior
- Avoid small or slow tank mates
Final Thoughts
Big freshwater fish need big care, but they offer big rewards. From peaceful Bichirs to playful Oscars and majestic Arowanas, each species offers something unique. Pick a fish that fits your tank size and experience level—and enjoy years of underwater enjoyment.
