Bristlenose Pleco in a River Tank: The Best Algae Eater for Current

If you only add one algae eater to a river tank, make it a bristlenose pleco. It stays small, it holds onto rocks in strong current with its sucker mouth, it works on algae around the clock, and it has a face only a mother could love, which is half the fun.

Why not a common pleco?

The "common pleco" sold as a small fish in most stores can grow well over a foot long and produce an enormous amount of waste. It outgrows almost every home tank. The bristlenose (Ancistrus species) usually tops out around 4 to 5 inches, and rarely reaches 6.

River tank fit

Excellent. Bristlenose plecos come from moving streams in South America and do well with flow and lots of oxygen. Their flat bellies and suction-cup mouths let them hang onto rocks and glass in the current, where most other bottom fish would get swept away.

They pair nicely with hillstream loaches, the other great rock-clinger for flow, as long as there's enough rock surface and algae for both.

Tank setup

• Tank size: 25 to 30 gallons or more for one. A 55-gallon river tank has room for a pair.
• Caves. Each pleco wants a hiding spot: a cave, a slate stack, or a gap under a root. Males guard their caves.
• Driftwood. Bristlenose plecos rasp on wood. Whether they get nutrition from it or just like it, most keepers find they do better with real driftwood in the tank. See our guide to preparing driftwood.
• Temperature: roughly the low 70s to around 80 °F.
• Clean water. They don't tolerate ammonia or nitrite spikes well. A cycled tank and regular water changes are a must.

What they eat

Algae is a start, but it's rarely enough in a clean tank. Feed:

• Sinking algae wafers a few times a week. See our algae wafer guide.
• Blanched vegetables: zucchini, cucumber, peas and spinach. Weigh a slice down with a fork or a veggie clip, and take out what's left the next day.
• Occasional protein: sinking pellets or frozen bloodworms.

If you see the pleco up at the glass all day, scraping desperately, it's probably hungry.

Males and females

Adult males grow big, branching bristles on their snouts. Females have only a few small bristles around the edge of the mouth, or none. A male in a cave with a female will often spawn, and he guards the eggs and fry himself.

Tankmates

Peaceful and easy: most community fish, shrimp and snails. They may chase other bottom fish away from their favorite cave, but they rarely hurt anything. Keep only one male per cave-zone in smaller tanks.

A few cautions

• They're nocturnal. You'll see more of them in the evening, or with a dim moonlight.
• They can get into filter intakes. Use a sponge over the intake.
• They can climb out of a tank in a riparium if the water's high and there's a path up and out. Keep the lid tight.

For other fish that like flow, see our best fish for strong-current tanks.

Sources (2)

FishLore: Bristlenose Pleco Care · Practical Fishkeeping: Bristlenose Catfish, the Hardworking Ancistrus

Photo by Hietaparta on Pixabay.

Related: Ten Fish That Thrive Best In A River Tank Style Aquarium (Riparium)