Flagtail Prochilodus Care Guide (Semaprochilodus taeniurus)

The Flagtail Prochilodus (Semaprochilodus taeniurus) is a striking freshwater fish known for its eye-catching appearance and unique behavior. It gets its name from the vibrant red and black striped pattern on its tail, resembling a flag waving in the water. Native to South America, particularly the Amazon River Basin, this species is a popular choice for large freshwater aquariums. The Flagtail Prochilodus is an herbivore with a peaceful temperament, making it a great tank mate for other large, non-aggressive fish.

Natural Habitat and Origins

The Flagtail Prochilodus is found in the Amazon River Basin, primarily in Brazil, Peru, and surrounding regions. In its natural habitat, this species inhabits slow-moving rivers, floodplains, and streams. The fish plays an important role in the ecosystem as a detritivore—feeding on algae, biofilm, and plant material that grows on submerged surfaces. This feeding behavior helps to maintain water quality by reducing algae buildup.

Appearance and Size

One of the most notable features of the Flagtail Prochilodus is its large, fan-shaped tail, which is adorned with alternating red and black bands. This "flag-like" tail contrasts beautifully with the silvery body, which is often marked by subtle spots and faint lateral stripes. The dorsal fin is similarly bold with hints of red and black, adding to the fish's striking appearance.

Flagtail Prochilodus can grow quite large in captivity, typically reaching up to 12-14 inches (30-35 cm) in length. Due to its size and active nature, it requires a spacious aquarium to thrive.

Aquarium Setup and Care

• Tank Size: A large aquarium is a must for the Flagtail Prochilodus. A minimum of 125 gallons (475 liters) is recommended to accommodate its size and swimming habits. A wider, longer tank is preferable to provide ample space for free movement.
• Water Parameters:
  • Temperature: 75-82°F (24-28°C)
  • pH: 6.0-7.5 (slightly acidic to neutral)
  • Water hardness: 2-12 dGH

The water should be clean and well-filtered, as Flagtail Prochilodus are sensitive to poor water conditions. Weekly water changes of 25-30% are essential to maintaining high water quality. A strong filter with good mechanical and biological filtration is recommended to manage the bioload in larger tanks.

• Aquascape: Flagtail Prochilodus enjoy an environment that mimics their natural river habitat. A substrate of sand or fine gravel is ideal, along with smooth rocks and pieces of driftwood. The fish will often graze on biofilm and algae that grow on hard surfaces, so incorporating such décor is beneficial for both aesthetics and the fish’s natural feeding habits.

Plants can be added to the tank, but be cautious, as the Flagtail Prochilodus may nibble on tender plants. Hardy plants like Anubias, Java Fern, and Amazon Swords can withstand some nibbling and are good options. Provide open swimming areas, as these fish are active swimmers.

Feeding

Flagtail Prochilodus are primarily herbivores, but they will also consume small amounts of protein from time to time. In the wild, they graze on algae, detritus, and plant material. In the aquarium, their diet should reflect this natural feeding behavior.

Recommended foods include:

• Algae wafers and spirulina-based pellets
• Blanched vegetables such as zucchini, spinach, lettuce, and peas
• Occasional protein supplements like brine shrimp, bloodworms, or insect larvae (in moderation)

It is important to feed them a balanced diet that is rich in plant matter. This will help them maintain their health and coloration. Because they are active grazers, they should be fed smaller amounts multiple times a day, allowing them to forage continuously.

Temperament and Behavior

Flagtail Prochilodus are generally peaceful fish that do well in community tanks, provided they are kept with similarly sized, non-aggressive species. However, due to their size and territorial tendencies, they can become mildly aggressive with smaller or slow-moving tank mates, particularly in confined spaces. They may also chase or harass fish that encroach on their territory, especially during feeding times.

Despite their potential for mild aggression, they are not overly hostile and will usually coexist peacefully with other fish in a large enough tank with plenty of hiding spots and swimming space. They are also known for their unique behavior of picking at algae and biofilm throughout the tank, often grazing on rocks, glass, and driftwood.

Best Tank Mates for Flagtail Prochilodus

Because of their size and somewhat territorial nature, it is important to select tank mates carefully. Suitable tank mates include:

• Larger peaceful fish like Silver Dollars or Bala Sharks
• South American cichlids like Severums, Uaru, or Angelfish (as long as they are not overly aggressive)
• Plecos (such as Green Phantom Pleco or Bristlenose Pleco) to help with bottom cleaning
• Other large, peaceful characins, such as Tinfoil Barbs or Pacu

Avoid smaller fish that may become targets of aggression or fish that are too slow to compete for food. Additionally, avoid highly aggressive species like large Central American cichlids, which may see the Flagtail Prochilodus as a competitor.

Breeding

Breeding Flagtail Prochilodus in captivity is rare and extremely difficult. In the wild, these fish are known to undertake seasonal migrations to spawn in specific areas, making it nearly impossible to replicate their natural breeding conditions in an aquarium. While spawning behavior has been observed occasionally in large public aquariums, there are no reliable reports of successful breeding in home aquaria.

For hobbyists who wish to attempt breeding, it would likely require a very large, well-maintained aquarium with specific water conditions mimicking their natural habitat, including changes in water flow, temperature, and diet.

Conclusion

The Flagtail Prochilodus is a beautiful and fascinating species that brings both color and unique behavior to large freshwater aquariums. With its peaceful nature, algae-eating habits, and striking appearance, it makes a great addition to a community tank with other large, non-aggressive fish. However, due to its size and care requirements, this species is best suited for experienced aquarists with ample space and a well-maintained tank.

By providing a spacious tank with clean water, a plant-based diet, and compatible tank mates, you can enjoy the beauty and charm of the Flagtail Prochilodus for many years to come.