XL Three Spot Headstander (5-6”)

• Scientific Name: Pseudanos trimaculatus

• Maximum Size: Up to 6 inches (15 cm)

• Lifespan: 8–10 years in well-maintained aquariums

Recommended Aquarium Size, Water Changes & Care:

• Minimum Tank Size:

  • 40 gallons (150 liters) for 1 Adult 75g+ for a group of 3 or more individuals (best kept in groups for comfort and natural behavior)

• Water Parameters:

  • Temperature: 75–82°F (24–28°C)

  • pH: 5.5–7.0

• Water Changes:

  • 30–50% weekly

  • Stability is critical—this species is sensitive to fluctuations and nitrate buildup

• Tank Setup & Care:

  • Provide dense vegetation, driftwood, and leaf litter to replicate their natural environment

  • Use a fine sand substrate to prevent mouth damage when foraging

  • Moderate flow and well-oxygenated water to simulate riverine conditions

  • Dim to moderate lighting with floating plants for cover

  • Use a secure lid—like many headstanders, they may jump when startled

  • Keep in groups of 5 or more to reduce stress and aggression

Diet:

• Feeding Type: Primarily herbivorous

• In the Wild: Scrapes algae, biofilm, and plant matter from submerged surfaces

• In Captivity:

  • Staple foods: algae wafers, spirulina flakes, veggie-based pellets

  • Hikari Minivore, Xtreme Nice Pellets

  • Supplement with: blanched vegetables (spinach, cucumber, zucchini)
    

  • Will graze naturally on tank biofilm and algae, which is beneficial for both the fish and tank health

Overview (Behavior & Compatibility):

Pseudanos trimaculatus is a peaceful and shy species of headstander with a distinctive trio of dark lateral blotches along a pale, streamlined body. It is one of the more community-friendly members of the Anostomidae family, showing far less aggression than Anostomus anostomus.

• Behavior: Peaceful, social, active grazers

• Tankmates:

  • Ideal companions include: peaceful South American species like Geophagus, Acara, hatchetfish, Spotted Silver Dollars, Corydoras, and plecos
    

  • Best results are achieved in a quiet, blackwater-style community tank

Natural Habitat:

• Distribution: Amazon Basin – Peru, Colombia, Brazil, Bolivia

• Habitat Type:

  • Calm, shallow creeks and tributaries with abundant submerged wood and vegetation

  • Tannin-rich blackwater environments with leaf litter and soft, sandy substrates

  • Often found in areas with mild to moderate flow and dappled sunlight through canopy cover

• Water Chemistry in Nature: Soft, acidic, and organic-rich waters, often with low conductivity

Breeding:

• In Captivity: Not yet successfully bred under standard home aquarium conditions

• Reproductive Behavior:

  • Believed to be egg scatterers with no parental care

  • Likely requires highly specific triggers such as:

    • Seasonal changes (simulating rainy season)

    • Very soft, acidic water

    • Slight drops in temperature

    • Increased feeding and water flow

  • Breeding in captivity remains undocumented and is extremely rare even in large public or research aquaria