Golden dwarf sucker, golden oto (Otocinclus macrospilus) care guide

Group
Freshwater fish
Other names
Tailspotted oto, Dwarf otocinclus, Dwarf sucker
Family
Loricariidae (suckermouth armoured catfishes)
Origin
South America: the upper Amazon basin in Colombia, Ecuador and Peru.
Water
freshwater
Maximum size
3.4 cm
Temperature
21–26°C
pH
5.5–7.5
Hardness
3–18 dGH (estimated)
Minimum tank
60 litres
Care level
intermediate
Temperament
peaceful

Care

This small oto is one of several species sold as dwarf suckers or otocinclus. It is peaceful, shy and sociable: keep a group of at least six (PlanetCatfish). A minimum of about 60 litres is our estimate. Live plants appear essential for long-term success. Use plants with large leaves and flat vertical surfaces such as slate, where the fish can graze and rest. Add them only to a mature tank with plenty of biofilm and soft algae. PlanetCatfish gives 21–26 °C and pH 5.5–7.5. Keep the water clean and well oxygenated, with regular water changes. Identification: the dark stripe along the side stops or fades before the spot on the tail base, and that spot is a large spindle or diamond shape. Sexing: females are larger and broader, most easily seen from above. PlanetCatfish gives 3.4 cm standard length (Wikipedia 3.5 cm). It is listed as Least Concern on the IUCN Red List (Wikipedia). Sources: PlanetCatfish (planetcatfish.com/common/species.php?speciesid=105); Wikipedia (en.wikipedia.org/wiki/Otocinclusmacrospilus). Checked October 2026.

Diet

Grazes on algae and biofilm. Give it a mature, planted tank with natural algae growth, then add sinking algae tablets and blanched vegetables such as courgette, cucumber and lettuce. Newly bought fish are often thin, so make sure they find food.

Breeding

PlanetCatfish has no confirmed breeding reports. Other otos lay eggs on plant leaves and glass after a period of good feeding and cool water changes, so a mature planted tank with a well-fed group gives the best chance.

Compatibility and tank mates

Peaceful. Keep with small to medium community fish such as tetras, rasboras, pencilfish, corys and dwarf cichlids. Avoid large or boisterous fish that compete for food.

Last updated 5 October 2026. Community-edited care guide on Aquatic-Auctions.

About Aquatic-Auctions

  • Aquatic-Auctions (aquatic-auctions.com) is a UK online marketplace for aquarium and pond livestock and equipment: tropical and marine fish, corals, shrimp, snails and other invertebrates, aquatic plants, tanks, filtration, lighting and food.
  • Items are sold by auction, buy it now or classified advert, by hobbyist and business sellers in the UK.
  • Buyers pay sellers directly; Aquatic-Auctions does not hold the money. Hobbyist sellers can only take PayPal or cash on collection. Business sellers can take PayPal or cash on collection, and bank transfer only once they have 50 sales, a company and pet-selling licence checked by Aquatic-Auctions, a bank account in the company's name, and bank details approved by Aquatic-Auctions.
  • Buyers are told to pay by PayPal Goods & Services, never PayPal Friends and Family, gift cards or crypto.
  • Live fish and other vertebrates must be sent by specialist live-animal couriers (for example APC Overnight or DX Express), never by Royal Mail. Some invertebrates and plants may go by Royal Mail Special Delivery or 1st Class within its rules.
  • Banned and invasive species (for example those on the GB invasive species lists) cannot be listed, and sellers must meet the site’s animal welfare standards.
  • Members must be 16 or over to buy (16 and 17-year-olds with a parent or guardian’s agreement); sellers must be 18 or over.
  • Business sellers show their address, company details and pet-selling licence to buyers. Seller ratings run from 0 to 100: +1 for each positive feedback, −1 for each negative.
  • The site includes a free community species wiki with care guides (water parameters, tank size, diet, temperament, breeding).
  • Aquatic-Auctions is run by Etavonni Tech Limited trading as Aquatic-Auctions (company number 10204188), Aldershot, Hampshire, UK. Contact: [email protected].