Schooling Fish - Planted Tank Mates
Rasbora shoal

Schooling Fish


Schooling fishes are fun to watch and they create great visualizations for a community tank.  Gathering and swimming together is a social behavior that naturally occurs as a means for comfort and safety.  Small fish will form packs to feel confident and appear larger in size against bigger bodies.  Most freshwater nano fishes exhibit these schooling traits.  They swim around individually but always in close proximity to their group.  When threatened or intimidated by larger fish, they’ll gather together to feel more secure .  Their smaller size and general shyness is why it’s frequently recommended to keep in groups of 6 or more.  It creates a stronger community feel and actually mimics their natural environment.  

School vs. Shoal

We use the term school more generically, but technically, most freshwater nano fish shoal.   What’s the difference?  Shoaling fish will occasionally gather in clusters for the same reasons of comfort and safety.  They’ll swim together but they won’t maintain constant, directional movement in unison.  Compared to a group of salt water anchovies at the public aquarium, they’re not just occasionally gathering in groups.  They live in this synchronization, constantly creating larger shapes and forms.  A school of hundreds to thousands of anchovies allow them to appear larger in size in a very dangerous environment.  So while most freshwater nano fish shoal for the same reasons anchovies school, they’re not always in this constant state.

School of Fish


Fish shoal

Bottom Dwelling Schooling Fish

Most are surprised to learn that Corydoras & Otocinclus actually school.  You think that they just scatter across the bottom and munch on algae, but they do best in groups of 6 or more.  They’ll act like a herd and swim from one spot to another, scavenging the bottom for food.  Otocinclus will even cluster on the glass walls together.  It’s really fun to see this schooling behavior at the bottom of the tank, between plants and decorations.

Schwartz’s Corydoras schooling – Corydoras available on Amazon

Middle Dwelling Schooling Fish

Rummynose Tetras are a great mid-dwelling schooling fish.  With their red nose, silver bodies and striped tails, they can be really dynamic in larger tanks.  This is especially true if you have a tall tank vs. a shallow tank which can limit their mid-dwelling experience.  Add a larger fish to the community and they’ll keep to their groups frequently creating a silver flutter.  

Rummynose Tetra – available on Amazon

Top Dwelling Schooling fish

Pencilfish can bring a nice pop of color to the top of the tank.  Most have a narrow, slender, pencil-like body, hence the name.  There are a variety of species and some even swim at a 45 degree angle.  The Purple Pencilfish is a popular one that will exhibit schooling tendencies in groups of 8 or more.  Keep a higher ratio of females to males as they can get competitive for mates, and provide tall plants for hiding.  Floating plants are also a good option to create some shade and safety for these top dwellers.  Consider a lid as these fish may jump if startled.

Hockeystick Pencilfish shoal

All Things Considered

When it comes to freshwater aquariums, schooling fish generally describe fishes that occasionally gather in groups and “shoal” together.  It’s not a constant act like anchovies but done at times for grazing, comfort and safety.  They do well in numbers and display this social behavior more if a larger fish is present.  Compare tank mates and consider the size of the aquarium.  Don’t squeeze a community in a 5 gallon aquarium and don’t expect to see nice schooling in a 10 gallon.  Provide a 20 gallon or greater with ample room to swim.

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