The Galaxy Otocinclus, scientifically known as Parotocinclus haroldoi, is a small and attractive species of armored catfish native to clear, slow-moving streams and rivers in central Brazil, particularly in the upper Rio Tocantins basin. It is prized in the aquarium hobby for its distinctive “galaxy” pattern of white spots on a dark brown to black background, peaceful nature, and excellent algae-grazing ability.

Adult Galaxy Otocinclus typically reach about 1.5 to 1.8 inches (4 to 4.5 cm) in length. They have a slender, elongated body covered in bony plates, with a dark chocolate or black base color adorned with numerous bright white or silvery spots along the sides, back, and sometimes fins. The belly is pale, and their head features a downward-facing mouth specialized for grazing on algae and biofilm. Males and females are similar in appearance, with females being slightly rounder when mature.

A tank of at least 10 to 15 gallons is suitable for a small group. Galaxy Otocinclus are highly social and should be kept in groups of six or more to reduce stress and encourage natural behavior. The aquarium should have a soft sand or fine gravel substrate, driftwood, rocks, and abundant live plants to maximize surface area for algae and biofilm growth. Provide plenty of hiding spots and shaded areas to help them feel secure.

Water parameters for the Galaxy Otocinclus should include a temperature range of 72 to 78°F (22 to 26°C), a pH between 6.0 and 7.5, and soft to moderately hard water. Pristine water quality, stable conditions, and regular partial water changes are essential for their long-term health.

Feeding Parotocinclus haroldoi is straightforward, as they are herbivores and thrive on natural biofilm, soft green algae, and diatoms. Supplement their diet with high-quality algae wafers, blanched vegetables such as zucchini or spinach, and occasionally spirulina-based foods. Ensure there is enough biofilm and soft algae available, especially for new arrivals.

Galaxy Otocinclus are peaceful and ideal for community tanks with other small, non-aggressive species such as tetras, rasboras, Corydoras, and dwarf cichlids. Avoid housing them with large or aggressive tankmates that may intimidate or outcompete them.

Breeding the Galaxy Otocinclus in captivity is rare but possible. Like other loricariids, they are egg scatterers and typically lay eggs on plant leaves or hard surfaces. Fry are delicate and need infusoria or finely powdered foods in the early stages.

Parotocinclus haroldoi (Galaxy Otocinclus) is a unique, gentle species that brings both beauty and functional algae control to peaceful, well-planted aquariums.