Flagtail Prochilodus (5.5”)

Scientific Name

Semaprochilodus taeniurus 

Maximum Size and Lifespan

• Size: Up to 14-18" in captivity; occasionally larger in the wild.

• Lifespan: Typically 8–10 years with proper care, though some may live longer under ideal conditions.

Recommended Aquarium Size, Water Changes, and Care

• Aquarium Size: A 180-gallon (680 L) tank minimum is recommended for a single adult; larger is preferable for a group. Juveniles can be raised in a 30-125 gallon tank for better observation

• Water Changes: Perform 30-50% water changes weekly to maintain excellent water quality. They are sensitive to poor conditions and produce significant waste.

• Water Parameters:

  • Temperature: 74–82°F (23–28°C)

  • pH: 6.0–7.5
    

• Care Level: Moderate to challenging due to size, activity, and space requirements. Provide powerful filtration, strong current, and ample swimming room. A tight-fitting lid is essential, as they are powerful jumpers.

Tankmates

• Compatible: Large Central/South American Cichlids, silver dollars, larger barbs, Geophagus, Severums, and larger catfish and plecos.

• Avoid: Small fish (which may be harassed or outcompeted for food), highly aggressive species like large Central American cichlids, and overly delicate fish.

• Best kept in groups of 3–6 if space allows, as they are naturally schooling fish.

Diet

• Omnivorous with strong herbivorous tendencies.

• In the wild, they feed on algae, detritus, and plant matter.

• In captivity, offer:

  • Spirulina-based flakes, pellets, and Wafers

  • Blanched vegetables Cucumber and Zucchini

  • Algae wafers

  • Frozen Bloodworms and Shrimp

• Constant grazing on biofilm and algae is natural, so encourage natural growth on rocks/driftwood.

Overview

The Flagtail Prochilodus is an active, strong-swimming characin prized for its striking black-and-red striped tail. It requires very large aquariums with strong water movement and should be kept with equally robust tankmates. Their diet leans heavily toward vegetable matter, and they serve as natural algae grazers. Though peaceful, their large size and constant movement make them unsuitable for small community tanks.

Natural Environment

• Native to South America, primarily in the Amazon and Orinoco River basins.

• Found in fast-flowing rivers and flooded forest areas, where they migrate in large shoals during seasonal flooding.

• Play an important ecological role by grazing on algae and organic matter.

Breeding

• Extremely difficult and rarely achieved in home aquariums.

• They are seasonal migratory spawners, requiring large river systems and environmental cues like water level changes, strong current, and seasonal flooding.

• No reliable reports of successful aquarium breeding exist; most specimens in the trade are wild-caught.

Summary: Flagtails are large, powerful, and active algae-grazing fish that thrive in huge, well-maintained aquariums with strong flow. They are best suited for experienced aquarists who can provide the space and care they require.