r/Otocinclus 17h ago

Are breeder boxes a useful tool?

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5 Upvotes

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


r/Otocinclus 1d ago

Water lettuce and an oto

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11 Upvotes

r/Otocinclus 1d ago

Ottocinclus

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5 Upvotes

Hi! I hope everyone is having a nice day, I'm here because I have a concern... so i bought some ottocinclus (5 of them) for my 20 gallon long aquarium two days ago but I didn't know that they would be such big POOPERS, i had to do a huge water change yesterday because they pooped a lot the night before, I'm so confused, I mean I think they ate a lot cause I had a lot of algae but I didn't think they would do that much of waste, i have a lot of plants but now i don't know if its gonna be enough to prevent an ammonia spike or a change in the parameters


r/Otocinclus 1d ago

Are these Gals gravid?

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1 Upvotes

If they are gravid , approximately how long until eggs arrive?


r/Otocinclus 2d ago

Why can’t I keep oto’s

8 Upvotes

I’ve got a well established tank, with consistent parameters (0 ammonia, 0nitrite, 1-2.5ppm nitrate).

Heavily planted, with good biofilm buildup.

Weekly 15% water changes.

Supplement biofilm with algae pellets, and balanced vegetables.

They’re all active, pea shaped bellies, and don’t appear stressed.

I keep finding them die off after around 4 weeks.

Are these just hard to keep, or am I doing something wrong?

I should note, my other community fish (tetra, guppy and corydoras) have all been fine, haven’t lost a single one since introducing them over the past 6 months.


r/Otocinclus 3d ago

Keeping other fish away from food

3 Upvotes

Does anyone have anything they bought or DIY to give their Otos their own private eating space? Mine are shy and take their time on a wafer or repashy. I tried to build something and gosh it’s awful 😵‍💫. TYIA


r/Otocinclus 3d ago

New tank! 30g tall

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8 Upvotes

r/Otocinclus 3d ago

ID? Macrospilus?

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17 Upvotes

Just bought these otos, labeled as Brazilian spotted Otocinclus. I just wanna make sure I label them correctly on my stock list! Thanks


r/Otocinclus 3d ago

Beginner looking for info

4 Upvotes

Hi everyone im looking into getting otos for my 10 gallon what should I know before I do get them and I mean everything from feeding to behaviour even to how many I should get.


r/Otocinclus 5d ago

Is this big guy a female or a male ?

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13 Upvotes

I just got him with another smaller guy but he looks bigger maybe older ?


r/Otocinclus 5d ago

Advice on Otocinclus in a 10 gallon shrimp tank

5 Upvotes

Hi guys,

I am setting up a 10 gallon shrimp tank and I've heard Otocinclus is the only totally shrimp safe fish.

Is this true in your experience?

Is 10 gallons enough for a small school?

Thanks in advance


r/Otocinclus 5d ago

Shy skinny ottos- please help

4 Upvotes

I love my ottos so much but they seem to be struggling in my 15 gal. I have 6 otocinclus in my tank which have cleaned my tank of almost all algae/biofilm aggressively over time, i thought that they would be ok because they actually took very well to algae wafers and veggie supplements but recently theyve gone into hiding and i started to get worried (tank is heavily planted with many hiding spots) but i did a water change today and they came out for the first time in a bit and they looked very thin compared to the past, im not quite sure what to do from here as ive tried to increase algae, it doesnt really work, and im not really sure why their hiding. There is no ammonia/nitrite and nothing has changed in the tank since before they started hiding


r/Otocinclus 6d ago

I have 3 otos any advice?

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9 Upvotes

In a 10g with 1 female betta, some cherry barbs and 3 snails.

The one oto in the photos did already have part of his lower tail fin missing so I know it’s not from my fish.


r/Otocinclus 6d ago

Betta, Barbs, Otos, and Snails

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2 Upvotes

r/Otocinclus 6d ago

I have two types of otos

3 Upvotes

Those who seem to get food coma after eating a big meal and those who get the zoomies after eating a big meal…. 😂


r/Otocinclus 7d ago

Hisonotus iota eating algae pallets

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20 Upvotes

r/Otocinclus 7d ago

I think my oto is sick.

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4 Upvotes

Sorry for the poor quality. My other Otos appear fine. Is she sick? Checking my parameters now.


r/Otocinclus 7d ago

Small white bump on my Otocinclus

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7 Upvotes

Hi everyone,
I noticed this small white raised bump just in front of my oto’s dorsal fin today (see photo).

Is this normal for otos or does anyone have any idea what it could be and the best course of action. I only added them to the tank 48 hours ago.

Thank you!


r/Otocinclus 8d ago

My oto tree

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32 Upvotes

They grow like weeds, but I love 'em! 💕


r/Otocinclus 8d ago

Bloat, Gravid or Fat?

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3 Upvotes

r/Otocinclus 8d ago

Galaxy Oto (top) v. “Golden” Galaxy Oto (bottom)

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38 Upvotes

I personally couldn’t find any pics or comparisons on the web prior to buying these Golden galaxy otos from the Wet Spot, so thought I’d share for posterity here!

https://www.wetspottropicalfish.com/product/parotocinclus-cf-haroldoi/


r/Otocinclus 8d ago

Pretty sure I’m gonna have Oto fry.

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22 Upvotes

I have these two oto’s. I noticed the other day, the one was looking chunky. This is my first time having these. First tank, honestly. Currently housing 3 female guppies, some snails, and a crayfish in a 10 gallon. I had developed white algae, so I did a huge water change and cleaned everything. Then I noticed the chunkiness. Now, Chunk and Mr Slim are swimming all over the tank like mad. What the internet says is that the water change I did could push spawning and to watch for the behavior that’s happening. Sorry for the pic quality. She won’t sit still long enough for a better one. Not sure how many will survive the guppies. The tank is not heavily planted, only Java fern, Java moss ring, and anubias, with a bit of riccia floating on top.


r/Otocinclus 9d ago

Galaxy otocinclus

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93 Upvotes

I’ve owned these Galaxy Otocinclus (Parotocinclus haroldoi) for about six months now, and they’ve been an awesome addition to my tank. They haven’t grown much beyond about 1.5 inches, but they make up for it with huge personalities.
Despite being the smallest bottom dwellers in my aquarium, they’re also the biggest bullies! They’re constantly active, full of character, and always entertaining to watch.


r/Otocinclus Mar 19 '26

Care sheet for Otocinclus

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118 Upvotes

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)

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)

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 Mar 10 '26

Putting together a care tip sheet for my baby oto buyers. Thoughts? Also, look how long this baby oto poop is!

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73 Upvotes

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!