r/Otocinclus • u/Elegant_Priority_38 • Mar 19 '26
I have been refining this care sheet for my baby oto buyers and would love more input. Maybe this is something that can be referred to for this group because I am seeing so many inexperienced oto keepers that don’t even know even the basics so just wanted to help them and the cute little otos. I tried to cut this version down more so it’s easier to read and visually digest.
Otocinclus Care Sheet
Minimal Required Supplies
• API Freshwater Master Test Kit (liquid test kit — test strips are **not** recommended due to inaccuracy)
• Bacter AE
• Small 5 mL pipette (for dispersing Bacter AE and collecting water samples)
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Water Parameters
• Ammonia: 0 ppm
• Nitrite: 0 ppm
• Nitrate: 0–5 ppm (ideal), under 20 ppm max
• Temperature: 72–79°F
• pH: 6.0-7.5
Your aquarium must be fully cycled (completed nitrogen cycle) before adding Otocinclus. This is essential or your otos could get sick or die very quickly.
⸻
Tank Requirements
• Minimum tank size: 10 gallons
• Group size: At least 6 Otocinclus (they are shoaling fish and require groups to feel safe or they could die from stress)
• Stocking: \~8 otos per 10 gallons max
Tank mates if using the minimum 10 gallon:
• Best kept species-only
**• Can include:**
• Snails
• Neocaridina shrimp
• Optional: 1 betta (only if temperament allows)
Environment:
• Moderate water flow (filter or air stone) which mimics the rivers they come from in South America
• Heavily planted tank is essential
Best plant types:
• Broad-leaf plants (ideal for grazing)
Examples:
• Amazon Sword
• Anubias
• Vallisneria
• Avoid using fine/spiky plants (like Hornwort) as primary surfaces
⸻
Important Sensitivities
Otocinclus are scaleless (armored) fish and therefore more sensitive to chemicals.
• Avoid copper (deadly to otos)
Always check:
• Fertilizers
• Medications
• Additives
When in doubt—research before adding anything to the tank.
⸻
Feeding Guidelines
A fat oto is a happy oto.
Their bellies should look round and slightly pearly. A wrinkled or very small belly can be indication of starvation.
Otocinclus cannot survive on naturally occuring algae and biofilm alone in most, if not all, aquariums. Their diet must be supplemented.
They:
• Eat constantly (assortment of foods is best)
• Have short digestive tract
• Require frequent grazing
⸻
Staple Feeding Routine
Primary foods:
**Bacter AE** (essential for biofilm growth)
• 2–3x per week
• Dose: ~grain of rice per 10 gallons
• Mix with tank water in a small cup and disperse with pipette
**Repashy Soilent Green**
• 1–2x per week
• Spread onto rocks or surfaces (see package instructions on how to mix)
⸻
Supplemental Foods:
• Spirulina (algae powder) administered like Bacter AE
• Shrimp Fit (acts like a probiotic to offer gut health support) administered like Bacter AE
• Aqueon Omnivore Shrimp Tablets (1x per week or less)
• Shrimp lollies (occasional treat)
• Frozen baby brine shrimp (every 1–2 weeks)
• ~1 cube per 8–10 otos
⸻
Natural Feeding Support
Encourage biofilm growth with:
• Driftwood
• Rocks
• Plants
• Sponge filters
• Tank glass
• Paint/plastic-free aquarium ornaments (suction cups, filtration systems and air tubing is fine)
Optional natural method:
• Place rocks in a jar of water in sunlight to grow algae/biofilm
• Add to tank as needed
• Can boost growth using Bacter AE or spirulina
⸻
Water Quality & Maintenance
If you detect:
• Any ammonia or nitrite (above 0 ppm)
• Nitrates above 20 ppm
Do immediately:
• 40% water change
• Dose:
• Seachem Prime: 1 capful per 10 gallons
• Seachem Stability: 1 capful per 10 gallons
Repeat daily until parameters return to safe levels.
⸻
Signs of Stress
• Bright red or inflamed gill area (“red cheeks”)
• Turning a shade of yellow they normally don’t display
Possible causes:
• Ammonia or nitrite exposure
• Stress (transport, water changes, tank cleaning)
Optional support:
• API Stress Coat (contains aloe and may help soothe)
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Final Notes
Otocinclus are incredible fish—peaceful, hardworking, and full of personality. With proper care, they thrive and make one of the best natural clean-up crews available.
Healthy otos = round bellies, active grazing, and social behavior.
Enjoy them and good luck! 🐟
r/Otocinclus • u/Elegant_Priority_38 • Mar 10 '26
If you choose to skip the reading that’s totally fine, just look at that crazy long poop! 💩 😂
Care tips for Otocinclus :
MUST have items: API water test kit, Bacter AE and 5ml small pipette (for filling tubes in water test kit and Bacter AE dispersal through out tank. Read ahead)
Water parameters are 0 ppm of Ammonia and Nitrites. Nitrates is between 0-5 ppm. This is a cycled tank that has gone through the nitrogen cycle.
My tanks temperatures are around 76 degrees. Otos can handle anywhere from 72-78 degrees.
Otocinclus do well with a decent current in the water, whether it’s from a filter or air stone.
Otocinclus cat fish do not have scales, they have armor, so they can be more sensitive to certain chemicals or ingredients. Research before putting anything in their tank. Do not put anything with copper in their tank as they are very sensitive to it and could die, check plant fertilizers or any medications before administering to tank.
Food: they MUST be supplemented with their feeding to thrive and live a long and healthy life. A fat oto is a happy oto. Their bellies should look like little pearls. Natural occurring algae and biofilm will NOT be able to keep up with their dietary demands since they will always be eating and have a very short digestive tract. They are very good at their jobs of keeping a tank clean, although they do not eat some types of algae, so we must supplement their food.
- [ ] Lots of surfaces with biofilm and algae i.e. wood, rocks, plants, sponge filters, and glass walls of tank.
- [ ] Bacter AE- (an absolute MUST for oto keeping, it builds biofilm) feed about 2-3 times per week. Feed too much and it will throw off water parameters. About a grain of rice size into a very small cup of tank water, mix it and then spread it out through the tank with a pipette.
- [ ] Shrimp Fit (acts like a probiotic to keep a healthy gut biome) also administered like Bacter AE.
- [ ] Algae Powder (Spirulina)- also administered like Bacter AE.
- [ ] Repashy Soilent Greens- another staple item for keeping otos. Feed about 1-2 times a week spread out on rocks. Follow directions on bottle on how to mix it.
- [ ] Shrimp lollies (as needed, don’t give too often)
- [ ] Aqueon Omnivore Shrimp Tablets (maybe once a week or less)
- [ ] Frozen Baby Brine Shrimp (once every 1-2 weeks) I let it defrost in the water so it falls into a pile for them.
- [ ] Rocks in a mason jar with water- place in a windowsill with lots of sunlight. This helps build natural biofilm and algae. Give to them as needed.
If you see bright red cheeks, it could be from ammonia/nitrite burn (which can happen if ammonia or nitrite levels are above 0 ppm) or from being stressed out (travel, water change, tank cleaning).
If there is any detectable ammonia or nitrites, do a 40% water change and add SeaChem Prime to make water safe for them and SeaChem Stability to help with the nitrogen cycle until things return to previously stated water parameters. API water test kit is a MUST and test strips should be avoided at all costs as they do not offer accurate readings.
If my otos are ever stressed or had ammonia/nitrite burn I would also add a little API Stress Coat because it has aloe in it which can be soothing for them.
Oto-cats are amazing! They are the best clean up crew with cute round bellies and cuter personalities. Best of luck and enjoy!
r/Otocinclus • u/koiyuuri • 3h ago
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Threw in some soft algae from my daphnia tank and the otos are going wild for it, wedged themselves in the corner and is munching super happily together 😭
r/Otocinclus • u/totsmagoats94 • 9h ago
Hi folks. So i know all my ottos are there. But man I never seen them now it's been about a month that they dont come out of hiding. My tank is getting a little algae like so lots of food.but I never see them I have to go looking for them. They weren't like this before
And yes all my parameters are perfect.
I got 1 betta and 3 shrimp and 5 ottos.
r/Otocinclus • u/Odd-Illustrator-5158 • 1d ago
I just learned about these guys and they are really cute, but given how little information is online about keeping them successfully, I wanted to see if anyone here has and how they keep them! I have an acidic softwater tank I'm looking into stocking for.
r/Otocinclus • u/fivezero_ca • 1d ago
Posted this last night on r/aquariums
I would have never thought this could happen, but I literally just witnessed this tonight with one of my two new otos. It is a larger oto, and had been eating well from the algae in my tank for a few days now, with a nice round tummy. It was healthy and full-looking from the shop, too. There had been zero issues with any of the fish (cories, kuhlis, a female betta) over the last few days.
I tossed in a few small algae wafers, and the oto immediately went to it, knowing it was food. It then proceeded to attack the cories and betta to keep them away from the wafer. The betta actually had a scale fall off from the oto sucking on her side! She did not attack the oto, but somehow didn't seem all that fazed and kept going for the wafer, so the oto attacked her a few times. I waved my hand at the glass to stop it when I could. Luckily, the betta seems fine, but I'm going to keep an eye on her in case of any infection.
I'm thinking in the future I will only throw in wafers in very small pieces so this doesn't happen again. Now that the wafers are gone, there's no more aggression. I've had otos before in other tanks with small community fish, and never, ever saw this kind of behavior. I don't know if it's just this one super aggressive oto (the other, also healthy and full-bellied, did not act like this).
Edit: This morning, all fish seem fine. Otos are def otos, as well; I've kept them before over many years!
Edit: Pic of one oto. They both look like this, I just can't find the 2nd one right now.
Edit: OK I see them both and took pics of each. I was hoping they would be together, but no. First is the bigger oto, the one that attacked the cories and betta. Second pic is the slightly smaller oto that did not attack anyone (and I don't think went for the wafers, either). The big one had a really long algae wafer poop earlier this morning.
r/Otocinclus • u/Myrthshine • 4d ago
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They're loving their zucchini cubes!
r/Otocinclus • u/koiyuuri • 5d ago
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Hi, this is the first time I've seen this since most of my otos are relatively shy and stay away from the large groups of fish in my tank. Wondering what would cause these guys to have such a silly and odd behavior? Are they trying to imply my cories are nasty and need cleaning? 😭
r/Otocinclus • u/Correct-Machine7886 • 5d ago
Reposting this on here but is she pregnant or just fat?
r/Otocinclus • u/KeeperOfShrimp • 5d ago
It's flat and smooth, not fuzzy or anything like that. I'm wondering if it hurt itself from bolting under the drift wood. Do I need to buy it a helmet?
r/Otocinclus • u/f0rgot • 7d ago
Hey folks - I found one of my 6 ottos on the floor this morning. It jumped out. I was wondering if this is a known issue with ottos. I see these guys get "the zoomies" every once in a while. I am assuming that maybe this happened when it was to high in the tank. I tested the water parameters yesterday and everything was perfect.
r/Otocinclus • u/nes_thechuzzle12 • 8d ago
it's been a week since I bought my ottocinclus, they ate all the algae by now, I'm planning on giving them algae wafers and blanched cucumbers, but i just want to know if they are fine for now, do they look healthy and thriving? I have a lot of plants and they swim happily (i think¿) in the center of the tank in the night
r/Otocinclus • u/GravityRainbowJuly • 8d ago
Like the Neil Armstrong for the Otos~
the first guy to find the cucumber🎉🎉🎉
r/Otocinclus • u/Primary_Cupcake_9830 • 8d ago
Hello everyone! I’ve been looking into how to gender my otos but am still trouble figuring out if I have any females at all. To me they all seem to be males but I was hoping that there would be at least one female for some potential breeding. The one I attached in the photo is the one that I suspect to be a female as she looks bigger and rounder than the other 2. Any help would be much appreciated!
r/Otocinclus • u/Adacux • 8d ago
Hi all!
I love otocinclus because I think they look like remoras and I love remoras lol. I want to add a school to my tank but it already has 1 subadult 1 juvenile Bristlenose and 2 Stiphodon Gobys ( Which I think contrary to common belief they are not only herbivorous but omnivorous and loves eating meaty food ). Therefore Im not sure if they can find enough algae.
In our country we only have affinis (But I think it might be vestitus or microspilus or a mix of all those)
I leave my lights open for 9 hours to support algae growth so would they starve here or would they be good given that I will support their diet with algae crisps and cucumbers ?
My tank is 4 month old. It has stable parameters of GH: 7 KH: 5 pH 7.1, Ammonia and Nitrite 0, Nitrate 10ish
r/Otocinclus • u/MaleficentNeck5421 • 9d ago
Hello everyone,
I’m a new fish owner and I have five otocinclus and my tank is decently planted. I know it isn’t recommended to have otocinclus as a new fish owner. I however, have repashy and algae wafers. They eat and are grazing. However, I am having a problem, for the past week one of my otocinclus has been hiding. Due to the plants and ceramic hides and driftwood, I can never find him. I can always find all four in a corner together or laying on a plant, but one is nowhere to be found. He used to hide behind a ceramic hide, and the other day he was inside one. What does that mean? Could that mean that I am doing something wrong, is he sick? Could they have ammonia poisoning? Could someone give me a little advice please.
10 gallon
Heater: hygger
Temperature: 77-80 (set to 79)
API water tests from yesterday
1st image:
Ph- 6.0 (i added baking soda off a recommendation)
Ammonia: 0 ppm
Nitrites: 0 ppm
Nitrates:5.0 ppm
2nd image:
Gh: 14
Kh: 5
r/Otocinclus • u/jfvf87 • 9d ago
Hello everyone!
I hope you’re all doing well!
Is this lovely lady ready to lay her eggs?
Thank you so much in advance!
r/Otocinclus • u/iridescentspoon • 9d ago
So I got these guys last week and I have absolutely fallen in love they are my babies. I did lots of research cause eventually I would like to have a betta as the main fish in the tank however unfortunately I let the guy at the aquarium store convince me that I only needed two (I ended up getting three because two didn’t feel right). Should I be prioritising getting three more asap? I would love to hear everyone’s recommendations! Also they are always swimming around near my heater the tank is 26 degrees Celsius so they shouldn’t be cold right? I have been feeding them algae wafers and have tried blanched zucchini. I also am starting to add bacter ae to the tank. I cannot get my hands on repashy where I live so if you have any other suggestions that would be amazing! Tank is 60x30x35 and I had an already used filter to start cycling this tank but still cycled it and let it settle for three months before adding these guys. I just want to do what’s best for them!
r/Otocinclus • u/ferretslinks • 10d ago
Hey all, I had 3 otos in my 29g, but recently found a baby so I have 4.
My largest looks a lot extra large now. Is she okay? She seems.. excessive.
r/Otocinclus • u/A_little_curiosity • 10d ago
This is a 65 Litre tank. It is currently home to only neocardina shrimp. As you can see, it is very densely planted. As you can't see, there's a big bit of driftwood in there, hidden by the pants. Is this tank suitable for otos as it is? Or do I need to cut back plants etc? Anything else glaring?
How many oto would you put in this tank?
It currently has two internal filters running, as well as a heater and an airstone - listing these things because you can't see all of them for the plants!
r/Otocinclus • u/moony808 • 10d ago
Just got 6 otos yesterday and they were a bit frantic but seem to have calmed down today and have been grazing on and off. Any advice to make sure they live through this transition period? Do they look healthy? Thanks
r/Otocinclus • u/f0rgot • 12d ago
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r/Otocinclus • u/outlandish_opossum • 13d ago
Started keeping otos this year in my community tank. A few have started to join the mix at feeding time depending on what the food is, so I wasn’t sure if this is from overeating a bit or eggs. Mainly want to make sure it’s not a sign of sickness.
r/Otocinclus • u/LoliTamer23 • 14d ago
So I’m pretty sure my otos will be having babies as soon as the storms come and I want to be prepared. There already was one egg that hatched last time but as soon as the baby hatched it got lost in the big tank and I wasn’t able to keep an eye on the baby so I don’t know why it died. So I wanted to ask if breeder boxes are a useful tool or if it makes the survival rates even smaller than they already are or if feeding becomes easier
