Flagtail Prochilodus Care Guide - Aquarium Setup, Diet & Breeding

The Flagtail Prochilodus is a large, streamlined South American characiform recognised for its attractive tail pattern and active, constantly moving nature. Its body is generally silvery to olive-grey, while the caudal fin carries bold dark markings that create the flag-like appearance behind the fish. Adults may also show subtle dark edging and a warm golden or reddish wash on the fins.

This species is an energetic shoaling fish that spends much of its time travelling through open water and grazing across submerged surfaces. It can be peaceful with appropriately sized companions, although its eventual bulk and vigorous swimming style make it unsuitable for small community aquariums.

In the wild, Flagtail Prochiloduses are associated with rivers, tributaries, floodplain environments and flooded forest. They feed as they move across the substrate and submerged objects, using their specialised mouth to scrape and collect algae, organic deposits and other edible material.

Like other Prochilodus relatives, Semaprochilodus insignis has a life cycle connected to seasonal river changes and migration. Its large adult size, schooling behaviour and need for extensive swimming space are important features of its natural history, not merely traits seen in captivity.

Flagtail Prochilodus is native to the Amazon Basin of South America, particularly Brazil, including the Amazon and Rio Negro drainage systems. It inhabits flowing rivers, tributaries, floodplain lakes and seasonally inundated forest waters.

A group requires a very large aquarium of at least 500 litres, with a practical footprint of around 180 cm by 60 cm; substantially larger is preferable as the fish mature. Provide long, unobstructed swimming lanes, strong but well-oxygenated circulation, secure equipment and a tightly fitted cover. Use smooth sand or fine rounded gravel to protect the mouth, along with robust driftwood, hardy plants or artificial planting, and shaded retreats around the edges while leaving the central area open.

Up to 30 cm (12 in) in total length. Females are often slightly deeper-bodied and may grow somewhat larger than males.

This species is primarily a grazer and detritus-feeder, naturally consuming algae, aufwuchs, biofilm, plant matter and organic deposits from submerged surfaces. In an aquarium it should receive a varied diet built around quality algae wafers, sinking herbivore pellets, spirulina-based foods and softened vegetables such as courgette, spinach or peas. Occasional frozen or prepared protein foods can be offered, but a heavily meat-based diet is not appropriate as the staple.

Flagtail Prochiloduses can live with other large, peaceful South American fish such as silver dollars, larger peaceful characins, severums, Geophagus, peaceful large cichlids and suitably sized suckermouth catfish. They are best kept away from highly aggressive cichlids, persistent fin-nippers and very delicate species. Small fish may eventually be at risk simply because of the Flagtail Prochilodus's size and opportunistic feeding behaviour, while slow or timid tankmates can be unsettled by its constant activity.

Breeding Flagtail Prochiloduses is not generally achieved in home aquariums. In nature, adults migrate into suitable river channels and spawn seasonally during periods of rising water, releasing eggs and milt into the current. Successful reproduction depends on very large volumes, strong flow, seasonal environmental changes and mature broodstock; commercial or research breeding may use specialised induced-spawning techniques.

Females are usually larger and fuller-bodied, particularly when mature or carrying developing eggs. Males tend to remain slightly smaller and more streamlined, but reliable visual sexing can be difficult outside the breeding season.