Boulenger's featherfin tetra

Where they come from

Boulenger's featherfin tetra (Bryconaethiops boulengeri) is an African characin, from the Congo basin region. If you have mostly kept South American tetras, these feel a little different - more "river fish" energy: built to cruise, quick to react, and they appreciate moving water.

They are not the most common fish in shops, so a lot of the battle is just giving them a calm start and not treating them like a tiny community neon-type tetra.

Setting up their tank

Think length over height. These are active, open-water swimmers and they look best in a group moving back and forth. A 4-foot tank makes life a lot easier, especially once they settle in and start putting on size.

• Tank size: I would start at 55 gallons for a proper group, bigger if you want tankmates
• Group size: 8-12+ if you can swing it (small groups stay jumpy)
• Flow and filtration: moderate to strong flow, with decent oxygenation
• Decor: open middle for swimming, plants/wood/rock to break lines of sight around the edges

For layout, I like a "riverbank" look: hardscape and plants along the sides and back, with a clear runway in the middle. They use that open space constantly.

Water-wise, they do fine in typical Congo-style community water. I have kept them happiest in the mid-70s F, neutral-ish pH, and clean water with regular changes. They are not super delicate, but they do get touchy if the tank is dirty or oxygen is low.

What to feed them

They are easy to feed once they are settled, but they can be shy the first week or two. Mine acted like food was suspicious until they learned the routine.

• Staples: quality flake or small/medium pellets that hold together in flow
• Frozen: bloodworms, daphnia, brine shrimp, mysis (mix it up)
• Live (optional but helpful): blackworms or live daphnia for conditioning and getting picky fish eating
• Veg matter: not a requirement, but a spirulina flake now and then does not hurt

If they share a tank with slower fish, target feeding helps. A feeding ring or dropping food into the current so it spreads out keeps the featherfins from hogging everything in one spot.

How they behave and who they get along with

These are schooling fish with a strong "follow the leader" vibe. In a good-sized group they are confident, always on the move, and way less skittish. In a small group they can turn into nervous glass-surfers that spook at every shadow.

Temperament-wise, they are not out to terrorize the tank, but they are quick and boisterous. Very small fish can get stressed, and anything tiny enough to fit in their mouth is taking a risk as they grow.

• Good tankmates: Congo tetras, larger barbs, Synodontis catfish, African butterflyfish (with caution), peaceful medium cichlids that are not fin-nippers
• Use caution with: long-finned slow fish (they are not classic fin-nippers, but chaos happens at feeding time)
• Avoid: tiny tetras/rasboras, newborn livebearers, shrimp you care about

Breeding tips

Breeding them in a home aquarium is possible but not something most people stumble into by accident. They are more like other egg-scattering characins: adults will eat eggs, and you usually need a separate setup if you are serious.

• Use a breeding tank with a mesh/screen or a thick layer of marbles so eggs fall out of reach
• Soft to moderately soft water and slightly cooler water changes can help trigger spawning
• Condition adults with frozen/live foods for a couple weeks
• Dim lighting and fine-leaved plants or spawning mops give them a target to scatter over

Fry are tiny at first, so you will need infusoria/microfoods early on, then graduate to baby brine shrimp. Keeping water clean without blasting them with flow is the balancing act.

Common problems to watch for

Most issues I have seen with this fish come from the tank being too small, too bare, or too low on oxygen. They will "tell" you by acting jumpy, clamping fins, hiding, or surfing the glass.

• Jumping: almost always a lid/gap problem, often triggered by sudden lights-on or chasing
• Skittishness: small groups, no cover, lots of foot traffic, or aggressive tankmates
• Thin fish that never fill out: outcompeted at meals, internal parasites (especially in new imports), or food too small/low-calorie
• Frayed fins: rough decor, bullying, or chronic stress from cramped quarters
• Ich/skin issues after purchase: common stress reaction if they arrive skinny or the tank is not stable yet

If one is hanging back and getting skinny, assume it is losing the food race. I have fixed that by spreading food across the surface, feeding twice a day for a while, and giving that fish a quieter corner with cover so it can relax and eat.