Galaxy otocinclus
Parotocinclus haroldoi
Also known as Haroldoi oto
FreshwaterFish

Care at a glance
- Temperature
- 75–82°F
- 24–28°C
- pH
- 6.0–7.5
- Adult size
- 1.6 in
- 4 cm
- Minimum tank
- 14 gal
- 54 L
- Temperament
- Peaceful
- Social behavior
- Social
- Swim level
- Bottom
- Diet
- Herbivore
- Difficulty
- Medium
- Breeding
- Medium
- Rarity
- Rare
- Family
- Loricariidae
- Origin
- Parnaíba basin, Brazil
Overview
The galaxy otocinclus is a tiny, speckled grazer for a mature, gently planted tank. It suits a keeper with a little experience.
Did you know
The galaxy otocinclus takes its common name from the pale flecks scattered across its dark body. They look like stars on a night sky.
Caring for the galaxy otocinclus
Give galaxy otocinclus a settled, gently planted tank of at least 14 gal (54 L), with wood, rock and a soft floor. Add them only once the tank has had time to build up a good coat of biofilm.
Keep the water soft to neutral, at 75 to 82°F (24 to 28°C) and a pH of 6.0 to 7.5. Hold conditions steady, with frequent small water changes.
They graze biofilm and soft algae from stones, wood and plants throughout the day. Their staple is the film that grows in a mature tank. Top it up with a little blanched vegetable and fine prepared grazing foods.
The galaxy otocinclus is social and does fine alone or in a group. Keep several together if you can, since a group stays confident and busy. They are small and peaceful, so keep them only with calm nano fish and shrimp. They have been bred in aquariums with moderate difficulty.
Good to know
Parotocinclus haroldoi is a member of the family Loricariidae and one of its smallest grazers.
In the wild
The galaxy otocinclus comes from the Parnaíba basin in Piauí, northeastern Brazil. It grazes stones and plants in the basin's warm, clear, gently flowing creeks. The Parnaíba is cut off from the great Amazon and Orinoco systems that supply most aquarium catfish. Fish from this river system rarely turn up in the trade.
Weekly picks
Tank mates
The galaxy otocinclus is a peaceful, social species that keeps to the bottom. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Marbled helogenes
Helogenes marmoratus
Freshwater3.1 in (8 cm) · 14 gal (54 L)73–82°F (23–28°C)
Gold-spotted halfbeak
Hemirhamphodon chrysopunctatus
Freshwater2.6 in (6.5 cm) · 14 gal (54 L)73–81°F (23–27°C)
Green lace shrimp
Atyoida pilipes
Freshwater2.8 in (7 cm) · 14 gal (54 L)73–82°F (23–28°C)
Vampire otocinclus
Nannoptopoma sternoptychum
Freshwater1.6 in (4 cm) · 14 gal (54 L)75–82°F (24–28°C)
Elegant pencilfish
Nannostomus limatus
Freshwater1.6 in (4 cm) · 14 gal (54 L)75–82°F (24–28°C)
Scherer's hatchetfish
Carnegiella schereri
Freshwater1 in (2.6 cm) · 14 gal (54 L)73–82°F (23–28°C)
Common questions
What size tank does a galaxy otocinclus need?
A galaxy otocinclus needs at least 14 gal (54 L). It spends most of its time in the bottom.
What temperature and pH does a galaxy otocinclus need?
A galaxy otocinclus is comfortable at 75–82°F (24–28°C) with a pH of 6.0–7.5.
What does a galaxy otocinclus eat?
A galaxy otocinclus grazes biofilm and soft algae from stones, wood and plants all day. Its staple is the film that grows in a mature tank, topped up with a little blanched vegetable and fine prepared grazing foods.
How big does a galaxy otocinclus get?
An adult galaxy otocinclus reaches about 1.6 in (4 cm).
Related species
1.6 in (4 cm)14 gal (54 L)72–81°F (22–27°C)Bahia parotocinclus
Parotocinclus bahiensis
1.6 in (4 cm) · 14 gal (54 L)
1.4 in (3.5 cm)14 gal (54 L)75–82°F (24–28°C)Peppermint otocinclus
Parotocinclus eppleyi
1.4 in (3.5 cm) · 14 gal (54 L)
2 in (5 cm)14 gal (54 L)72–81°F (22–27°C)Ceará parotocinclus
Parotocinclus cearensis
2 in (5 cm) · 14 gal (54 L)
2.4 in (6 cm)14 gal (54 L)75–82°F (24–28°C)Gold spot otocinclus
Parotocinclus spilosoma
2.4 in (6 cm) · 14 gal (54 L)
2.4 in (6 cm)20 gal (75 L)72–81°F (22–27°C)Pit bull otocinclus
Parotocinclus jumbo
2.4 in (6 cm) · 20 gal (75 L)
2.4 in (6 cm)14 gal (54 L)72–81°F (22–27°C)Red fin otocinclus
Parotocinclus maculicauda
2.4 in (6 cm) · 14 gal (54 L)