The Otocinclus catfish

Commonly known as the "Oto cat," is a small freshwater fish renowned for its distinctive appearance and beneficial attributes. This species, scientifically classified as Otocinclus affinis, belongs to the family Loricariidae and is native to South America. With its charming looks and effective algae-eating abilities, the Otocinclus catfish has become a beloved choice for aquarium enthusiasts worldwide. In this article, we will explore the characteristics, care requirements, and benefits of keeping Otocinclus catfish in your freshwater aquarium.


Otocinclus catfish possess a unique body shape and coloration that sets them apart from other aquarium fish. They are small in size, typically reaching 1.5 to 2.5 inches (4-6 cm) in length. Their bodies are elongated and slender, with a flattened belly. These catfish have a translucent appearance, displaying a light to olive green coloration on their bodies, which helps them camouflage in natural environments.


Otocinclus catfish are peaceful and social creatures that thrive in groups. It is recommended to keep them in schools of at least five individuals to promote their well-being and reduce stress. They are known for their calm demeanor and seldom display aggressive behavior towards other fish species. Due to their peaceful nature, Otocinclus catfish make excellent tank mates for various community aquariums. They are compatible with a wide range of peaceful fish, such as tetras, guppies, rasboras, and dwarf cichlids.


To provide a comfortable and healthy environment for your Otocinclus catfish, it is important to consider their specific tank requirements:

1. Tank size: A minimum tank size of 10 gallons is recommended for a small group of Otocinclus catfish. However, a larger tank will provide them with more swimming space and allow for a greater variety of plant and hiding spots.

2. Water parameters: Otocinclus catfish prefer slightly acidic to neutral water conditions. Maintain a pH range of 6.8 to 7.5 and a temperature between 72-79°F (22-26°C). Ensure the tank is well-filtered and provide gentle water movement to mimic their natural habitat.

3. Substrate and vegetation: Utilize fine-grained sand or smooth gravel as a substrate to prevent any injuries to their delicate barbels. Otocinclus catfish appreciate a well-planted tank with plenty of hiding spots, such as driftwood, caves, or dense vegetation.


One of the key benefits of keeping Otocinclus catfish in your aquarium is their exceptional algae-eating abilities. These catfish are excellent natural cleaners, consuming various forms of algae that accumulate on plants, decorations, and glass surfaces. However, it is important to note that they may not solely rely on algae for a balanced diet. Supplement their diet with high-quality sinking pellets or wafers specifically formulated for herbivorous fish. Additionally, occasional feedings of blanched vegetables like zucchini, cucumber, or spinach will provide essential nutrients.