Otocinclus Catfish
Otocinclus macrospilus
Also known as Oto, Dwarf Sucker Catfish, Otocinclus vittatus
Edited by Ivan F. · Reviewed
Beginner verdict
A tiny, gentle algae grazer that works in groups across plant leaves and glass. Many are wild caught and arrive thin, so they do best in a mature, planted tank with plenty of algae. It is a lovely clean-up fish once settled, and completely safe with shrimp.
Care at a glance
- Min tank size
- 11 US gal
- Footprint
- 18 x 12 in
- Temperature
- 70–79 °F
- pH
- 5.5–7.5
- Hardness
- 1–12 dGH
- Swim zone
- Bottom
- Min group
- 6 fish
- Lifespan
- 3–5 years
Otocinclus Catfish care mistakes to avoid
The mistakes beginners most often make with this species.
- Do not buy just one or two. Keep at least 6 fish so they feel secure.
- Add only to a mature tank. New tanks rarely have enough algae to feed them.
- Look for full bellies when buying, since many arrive starved and weak.
- Do not expect them to control heavy algae. Treat the cause instead.
- Check your tank before you buy. Our sourced minimum is 11 US gallons.
Otocinclus Catfish tank mates and swim zone
Bottom
Spends most of its time in this part of the tank.
Paracheirodon innesi
Paracheirodon axelrodi
Hyphessobrycon amandae
Hyphessobrycon herbertaxelrodi
Hemigrammus erythrozonus
Trigonostigma heteromorpha
Tanichthys albonubes
Their temperature ranges barely overlap, so you will have little room for error.
Betta splendens
Betta often does best alone. Only try this in a larger, planted tank, and watch closely.
Ancistrus cirrhosus
Bristlenose Pleco is much larger than Otocinclus Catfish and may frighten or even eat it.
Crossocheilus oblongus
Siamese Algae Eater is much larger than Otocinclus Catfish and may frighten or even eat it.
Xiphophorus hellerii
Swordtail is big enough to eat or bully a fish as small as Otocinclus Catfish.
Mikrogeophagus ramirezi
Their temperature ranges do not overlap, so one of them would always be stressed.
Melanotaenia boesemani
Their temperature ranges do not overlap, so one of them would always be stressed.
Otocinclus Catfish feeding and care
How to feed
- Let them graze biofilm and soft algae on plants and glass.
- Add algae wafers and blanched zucchini if their bellies look thin.
- Feed small portions you can see finished within a couple of minutes, because overfeeding fouls the water fast.
Telling males from females
Females are larger and rounder, especially when viewed from above.
Plants that suit it
Species facts
- Family
- Loricariidae
- Native to
- South America
- Adult size
- 1.4 in (3.5 cm)
- Temperament
- Peaceful
- Social needs
- Schooling/Shoaling (6+)
- Diet
- Algae Grazer
- Water flow
- Gentle
- Substrate
- Any
- Live plants
- Yes - Loves Plants
- Shrimp
- 100% Safe
- Fin nipping
- None
- Vulnerable to nippers
- No
- Breeding
- Difficult in Home Tanks
Otocinclus Catfish FAQ
What size tank do Otocinclus Catfish need?
Our sourced minimum is 11 US gallons (41 liters), with a footprint of 45 x 30 cm. A bigger tank is always easier to keep stable.
How many Otocinclus Catfish should I keep?
Keep at least 6 fish. Bigger groups usually look better and behave more confidently.
What can live with Otocinclus Catfish?
Good matches on our list include Neon Tetra, Cardinal Tetra and Ember Tetra. Avoid Endler's Livebearer and Swordtail.
How long do Otocinclus Catfish live?
Care guides report about 3–5 years. Stable water and a good diet make the biggest difference.
Why do my otocinclus keep dying?
Starvation and shipping stress are common causes. Buy well-fed fish, add them to a mature tank, and offer vegetables if algae runs short.
Where to buy Otocinclus Catfish
We have not found a store that sells Otocinclus Catfish under its scientific name yet. We add stores as we confirm them.
Live animals and plants travel by courier. Check the store's live-arrival guarantee, and only buy once your tank has cycled (see how to cycle a fish tank).
Some US states restrict certain species. Check our US state aquarium rules table and your state's own rules before you buy.
Complete the tank
The essentials for a small, gently filtered tank.
Tank size for this species
At least 11 US gallons (41 L), 45 x 30 cm footprint
Filter
Air-driven sponge filter
Gentle flow that small fish and long fins can handle, plus a safe home for good bacteria.
Aquarium Co-Op Coarse Sponge Filter (Small) US
Fluval AquaClear 20 Power Filter US
Tetra Brillant Filter Spain
Fluval AquaClear 20 Power Filter Spain
Why we chose these (Best Filter for a 10-Gallon Tank). Nobody here has used or tested them.
Heater
Adjustable heater, about 5 W per gallon: 25 W at 5 gallons, 50 W at 10
Keeps a small tank stable. Adjustable models let you set the temperature your species needs. Size up for a cold room.
Fluval T50 Fully Electronic Aquarium Heater US
Aqueon Pro Adjustable Heater 50 W US
Fluval T50 Fully Electronic Aquarium Heater Spain
Eheim Thermocontrol e 50 Heater Spain
Why we chose these (Best Heater for a 10-Gallon Aquarium). Nobody here has used or tested them.
Water Conditioner
Dechlorinator such as Seachem Prime
Tap water contains chlorine or chloramine that harms fish.
Seachem Prime US
Fritz Complete Water Conditioner US
API Betta Water Conditioner US
sera aquatan Spain
Tetra AquaSafe Spain
Maker's page · Sold at Kiwoko · Sold at Tiendanimal · Sold at zooplus.es
Why we chose these (Best Water Conditioner for Betta Fish). Nobody here has used or tested them.
Test Kit
Liquid kit such as API Freshwater Master
Tracks ammonia, nitrite, nitrate and pH while the tank cycles.
API Freshwater Master Test Kit US
API General & Carbonate Hardness Test Kit US
Maker's page · Sold at The Shrimp Farm · Sold at Bulk Reef Supply
sera aqua-test box (Cl) Spain
JBL PROAQUATEST COMBISET Plus NH4 Spain
Why we chose these (Best Test Kit for a Freshwater Aquarium). Nobody here has used or tested them.
Cycle the tank before adding animals. See our guide on how to cycle a fish tank.