# Are Otos more sensitive to Co2 than other fish?



## Sacha (24 Apr 2015)

Hi all, 

I have had a lot of trouble keeping otocinclus alive in my high-tech planted tank. There is plenty for them to eat, and I cannot see of any particular reason why they always seem to get sick and die. 

The fish appear healthy in all other respects (they have full bellies, gills not particularly red). 

Is it Co2 toxicity? My other fish (tetras, barbs, cory) don't seem bothered in the slightest by the Co2. But do the Otos have a lower tolerance for Co2 than these other fish? 

Cheers.


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## karla (24 Apr 2015)

I can not say if they are more susceptible than other species in general, but the ones I tried were definitely more delicate than other fishes and seem to take quite a long while to acclimatise.


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## Andy Thurston (24 Apr 2015)

mine are a little more sensitive than the glowline tetras in the same tank. they tend to get pink gills with higher co2 and they go pale too


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## zozo (24 Apr 2015)

They are well known to stress easily and also die of it. They seem to be very hardy when it comes to water quality, but stress is the most commen cause for them to perish. Keep on watch, specialy at night, they maybe harassed  by some barbs chasing them or maybe by some other fish.


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## Sacha (24 Apr 2015)

Thanks for all the replies. I'll keep a close eye on them to make sure they're not being pestered by the other fish.


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## zozo (24 Apr 2015)

I do not know what kind of barbs you're holding. I guess keep an eye on them, some barbs have the habbit to harass other fish.. Tiger barbs are the best example, they love to chase and nibble fins..


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## Sacha (24 Apr 2015)

Pentazona, they are pretty placid. It could be the silvertip tetras causing aggro.


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## zozo (24 Apr 2015)

An other thing with the oto's is, a heavily planted tank with co2 will also be heavily oxygenated. In a tank like that oto's will be very active during day and night. They are very playfull and will look like they never get tired playing all around the tank. If an oto is inactive for longer periods and hiding a lot, thats a sign for them being stressed or not feeling safe. Which you often see in poorly planted tanks like in some aquarium shops. Just laying on the bottom feeling unsafe not tracking attention.


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## dw1305 (25 Apr 2015)

Hi all, 





Sacha said:


> But do the Otos have a lower tolerance for Co2 than these other fish?


 I think they are quite sensitive to high CO2. A lot of Loricariids are. Apparently they will gulp air like a _Corydoras, _but I've never seen mine do this.   





zozo said:


> In a tank like that oto's will be very active during day and night. They are very playfull and will look like they never get tired playing all around the tank. If an oto is inactive for longer periods and hiding a lot, thats a sign for them being stressed or not feeling safe.


 I've found that they become quite nocturnal as they get older, they only become active in the evenings and at night. One of mine is at least 4 years old, so they are potentially quite long lived for a small fish.

cheers Darrel


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## zozo (25 Apr 2015)

dw1305 said:


> Hi all,  I think they are quite sensitive to high CO2. A lot of Loricariids are. Apparently they will gulp air like a _Corydoras, _but I've never seen mine do this.    I've found that they become quite nocturnal as they get older, they only become active in the evenings and at night. One of mine is at least 4 years old, so they are potentially quite long lived for a small fish.
> 
> cheers Darrel



 I dont want to nitpick, but 80 % of the pleco family branch are found in swift flowing clear well oxygenated streams. In invironments like that they thrive best. Actualy almost all available pleco's on the market need a special tank to meet these conditions and 90% of the owners don't, becuase the fish looks healthy and strong and can do in lesser conditions then optimum. All a fish can do is breath, eat and swim and if you see a change in that you're already welll to late with doing your home work. 

I guess we're all doing our homework and if we keep fish with our plants we should have acceptable numbers when we talk high levels of co2 which also means high oxygen levels. If you combine this with a steady flow, your oto will feel like in heaven and shoot through your tank like little dart arrows with sucker cups.. Anyway, if the co2 is level excels the oxygen level that much so an oto will die of it then you don't have a fishtank but a torturechamber, where even a goldfish wouldn''t feel very well..


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## Sacha (25 Apr 2015)

I have high Co2 levels, but massive steady flow and (I think) high oxygen levels. My ottos are all inactive day and night. It's rare that I see them move.


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## Julian (25 Apr 2015)

As someone who has nuked their tank with CO2, my Ottos were actually the last to die. The SAE's and Galaxy Rasboras were the first to go.


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## zozo (25 Apr 2015)

These are my oto's  in the tank since yesterday morning, 7 of them helping the 7 shrimps. The rest is not home yet. In the shop they all where just still on the bottem not at almoving around. I brought them home and the feast began. Actualy i don't know them other than this in my tanks, i've bein without tank for a great deal of time, but oto's haven't changed. Always on the move playing and shooting around the tank day and night. Unfortunately not the best nor most beautiful vid at the wrong time of day, shot 25 minutes ago, just as a reference for you how oto's should act. When i put the camara away they come to the front of the tank, like they are pestering me. And this a fairly new tank, heavily planted, but not grown in yet.


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## dw1305 (25 Apr 2015)

Hi all,





zozo said:


> I brought them home and the feast began.


Do you feed your _Otocinclus_ vegetables?

cheers Darrel


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## dw1305 (25 Apr 2015)

Hi all,





zozo said:


> I dont want to nitpick, but 80 % of the pleco family branch are found in swift flowing clear well oxygenated streams. In invironments like that they thrive best. Actualy almost all available pleco's on the market need a special tank to meet these conditions and 90% of the owners don't, becuase the fish looks healthy and strong and can do in lesser conditions then optimum.


 I'd definitely agree with that. A lot of plecs are rheophilic, and people who keep them need to understand that they require specialist care.

Fish like _Hypancistrus_ will still gulp air when they are oxygen stressed, although they have lost the specialized gut morphology that would allow them to extract any oxygen from it. The ability to extract atmospheric oxygen is thought to have been inherited from the common ancestor of the Loricariids and Callichthyidae, and is retained in <"Common Plecs etc. which are tolerant of low oxygen"> (I assume the fish was actually a <"_Pterygoplichthys"> sp._ plec ).

I got to know a couple of Bristol plec breeders and because of this I became aware that even really skilled fish keepers were losing large rheophilic plecs to low oxygen levels. I wrote an article that covers oxygenation specifically for Plec keepers - <"_*Aeration and dissolved oxygen.....*_">, it has had a few homes, but currently resides at <http://plecoplanet.com/?page_id=829>. I'm biased, but if I could only keep one article on fish keeping, and had to destroy all the others, I would keep this one. 





Julian said:


> As someone who has nuked their tank with CO2, my Ottos were actually the last to die. The SAE's and Galaxy Rasboras were the first to go.


I'd expect all these fish to be susceptible to low O2/ high CO2 (from <http://www.ukaps.org/forum/threads/co2-ph-level-in-planted-tank.26559/page-2>). 





dw1305 said:


> <"Fish Respiration">. As a general rule fish from cool, fast flowing, highly oxygenated water (Hill stream Loaches (_Sewellia lineolata_ etc., some "L." numbers (_Chaetostoma spp, Pseudolithoxus spp. etc., Salmonids_) are most at risk from high CO2, and for the same species large fish are more at risk than small fish (due to the differences in the body volume (^3) to gill area (~^2) ratio).


cheers Darrel


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## zozo (25 Apr 2015)

dw1305 said:


> Hi all,Do you feed your _Otocinclus_ vegetables?
> 
> cheers Darrel


Not yet  but i will if they need.. For now there is plenty in the tank, that's why they are the first to arive after the shrimps. There are also a bunch of snails which came with the plants. And i see them grow daily at an exeptional rate. That means food in the tank. I never over feed my fish and even if you think you see nothing, but there is always food in a healthy tank, like in nature. Fish have a very slow metabolism and they are very easily over fed. Let them work for it, like we have too, i just keep a close eye on them and feed as scarcely as posible. They don't need to be fat and lazy. I have something like a little pond in the yard with a lot of elodea, i rather take a bit of choped elodea with some algea on it then cucumber or carrot all the time. elodea is very good food for most fish.


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## dw1305 (25 Apr 2015)

Hi all, 





zozo said:


> Not yet  but i will if they need......Fish have a very slow metabolism and they are very easily over fed. Let them work for it, like we have too, i just keep a close eye on them and feed as scarcely as posible.


OK, they look fine and have settled in well, but it is a little different with _Otocinclus_, because they are specialized feeders on a relatively small range of aufwuchs, they basically graze all the the time when diatoms are present. If diatoms aren't present they search for a new source of food, they don't know they are in an aquarium, so they just continually swim around looking for "new" grazing surfaces. Unless you have a huge planted aquarium, and relatively low stocking, they will rapidly exhaust all the natural food sources, become starved and stressed and eventually just waste away. People often say that their _Otocinclus _dying wasn't a food issue, because they had "_plenty of algae", _but most algae isn't food for _Otocinclus_.

As well as plants and hard surfaces they will also <"graze leaf litter">, I haven't tried _Elodea,_ but it may well work as a food as it begins to decompose. They like dried Nettle leaves, Kale, Spinach etc but you need to leave them in the tank until they begin to go slimy.

Unless you have a huge tank for long term success you need to get them to feed on an alternative food source (still low in nutrients, I feed mine Bell Pepper, Courgette and Cucumber) and then they will begin to show more natural behaviour, where they spend a lot of time resting on _Echinodorus_ leaves etc. (often communally) and become active in the evening and over night. 

cheers Darrel


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## Sacha (25 Apr 2015)

Thanks for the info Darrel. What's the best way to supplement their diet then, kale and spinach? Do you blanch it first or just chuck it in raw?


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## dw1305 (25 Apr 2015)

Hi all,





Sacha said:


> What's the best way to supplement their diet then, kale and spinach? Do you blanch it first or just chuck it in raw?


 Blanch it, it just helps it break down a bit quicker. I have dead leaves in all the tanks, but the leafier vegetables need to be off the bottom if you have snails. 

I don't bother blanching the courgette, pepper or cucumber, but I have a lot of snails so the vegetable surface is rapidly eroded. I fasten the slices of vegetables about 2/3 up an upright bamboo cane (just with an elastic band), and put it in the flow, this keeps some of the smaller snails off, but usually I have to replace them every couple of days. 

There are quite lot of threads on the Loricariid forum of "PlanetCatfish" about feeding adults (and fry) of a range of "vegetarian" plecs, including _Otocinclus.
_
cheers Darrel


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## sciencefiction (26 Apr 2015)

Otocinclus are adapted to survive in low oxygen conditions, because they gulp air but if you see them gulp air often, there's something wrong going on in the tank. I've seen a video of them about some of their natural habitats, alongside corydoras, the only ones surviving the dry season and appalling water conditions due to them being capable of gulping air at the surface.  So they are quite hardy that way but one shouldn't have "a dry season" in their tanks at any stage. The rest of the fish will suffer faster for sure.

My common pleco got stressed when I overdosed with liquid carbon, he'd gulp air several times a day and he doesn't do it at all normally. So they may get stressed by various factors. He'd also gulp air during a water change and I do 50% at a time and my tap water is saturated with CO2. I don't know if that plays a role in the gulping or it's the actual fact all filtration is off during a water change but I always have an air stone running all the time.

I'd imagine injected CO2 at high levels are a different ball game and some fish are less tolerant than others and it has nothing to do with oxygen content. They may not even gulp air but just stay lethargic instead. 

My ottos will not try eating vegetables if there's enough suitable algae in the tanks. But then again 4 of mine are in a 90G tank and they always seem to find something. My other 3 are pretty much to themselves in a 120 litre with a few kuhli loaches that don't compete with them for food and cherry shrimp. My baby otto, who I raised on zucchini, has not been seen touching zucchini after the first couple of months. I am guessing he prefers other food available in the tank. In this tank, they do go for spirulina sticks from time to time, or at least gather alongside the shrimp when I drop this food so I am guessing they are attracted to it.  I do drop veg at least once a week, they don't touch it at all....But my guess is hungry ottos will.
I also have leaf litter in that tank constantly so as Darrel suggests that maybe helping along.


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## BigTom (26 Apr 2015)

My observations agree pretty closely with Darrel's - I have 12 otos in a 600l tank which is stuffed full of wood and leaf litter to graze on. I don't specifically feed anything else for the otos but they are outrageously fat from biofilm grazing and I see very little activity from them during the day. Highly active otos = underfed otos in my book.


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## naughtymoose (26 Apr 2015)

That's a really informative article Darrel. Thanks for sharing it with us.

I've tried feeding courgette and also peppers to my Otos (I have two of the _*Hisonotus*_* notatus*_)_ they don't seem to go for it though.

I use Fish Science mini algae wafers; they like those. The 5 *Desmopuntius pentazona* (Pentazona Barb) and also my three *Corydoras habrosus *(Salt and Pepper Catfish) seem to enjoy them.

I think that I'll get hold of some good leaf litter to hide away, a bit of a natural, wild corner. I have plenty of nettles available, as I have a planter with them in a corner of the garden. Do they need to be dried first? What about freezing them first to break down the structure?


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## markk (26 Apr 2015)

BigTom said:


> Highly active otos = underfed otos in my book.



Couldn't agree more. Mine are well fed and are generally inactive during the day, only starting to move around when the lights are dimmed/off.


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## sciencefiction (26 Apr 2015)

markk said:


> Couldn't agree more. Mine are well fed and are generally inactive during the day, only starting to move around when the lights are dimmed/off.



Well, then mine have been underfed for 4 years and grown huge being underfed. I think that's not the way to judge things. Mine are quite active during the day although they really shine at night. They play rounds on the glass just like my clown loaches do, chasing each other, nothing to do with food or the lack of it I think.


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## zozo (26 Apr 2015)

sciencefiction said:


> My ottos will not try eating vegetables if there's enough suitable algae in the tanks..



Today i did put some blanched cucumber in my tank, the oto's don't even bother looking at it and graze around it.. Only the shrimps are interested a bit but more looks like curiousity than hunger. And the tank looks pretty clean by now.. But still there seems to be something in there for them they prefere above the vegies.  Quite interesting all those diferent experiences. Also did put some garlic in there and the shrimps seem to prefer that more. They realy seem to love it. My goldfish in the pont also love garlic.


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## sciencefiction (26 Apr 2015)

Yes, my shrimp finish the veg, the ottos don't take any looks at it. But if you buy new ottos, they most certainly jump on the veg straight away, meaning they are quite starved from where they come from but eventually stop eating it.  Also, I suppose, if you keep lots of ottos, you need supplementing with veggies a lot.


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## dw1305 (26 Apr 2015)

Hi all,





naughtymoose said:


> Do they need to be dried first? What about freezing them first to break down the structure?


Either will do. "Racoll" on "PlanetCatfish" uses <"frozen spinach">, he is an Ichthyologist and has worked a lot in S.America. 

cheers Darrel


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## Tim Harrison (26 Apr 2015)

Mine have never been the slightest bit bothered by high CO2 even when my equipment played up and nearly gassed my other critters they were swimming around without a care in the world behaving quite normally. But mine have always darted up to the surface to gulp air even in my low-energy tanks which have always been very well oxygenated.
They posses digestive tract adaptations that allow them to "air breath" it's a diagnostic trait of the genus apparently. Loricariids are mostly facultative air breathers but I've heard/read somewhere that that may not be true of all oto species...in that some maybe obligate air breathers


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## sciencefiction (26 Apr 2015)

I think a combination of things works for ottos.. driftwood, smooth round stones on the bottom, plants, leaf litter and some veg supplements when needed. I don't think I ever clean the glass in my tanks so it doesn't have to be an algae ridden tank glass, it's probably the biofilm and mine graze a lot on the glass due to being in tanks with just a few plants.

As for gulping air, mine do it extremely rarely. I might not see them for months or a year doing it. 4 of mine are in a tank next to my sofa so I see them all the time. I really love looking at them, that's why.
  Maybe it depends on the species. I've got a few different ones for sure, the only one I can recall the name of is zebra otocinclus. But I have a lot of surface movement and flow in my tanks. Both tanks with ottos have trickle filters as well which could be playing a role. I've got very fast evaporation because of it which helps with oxygen exchange to an extent.


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## zozo (26 Apr 2015)

I do nightlight simulation with the RGB strip.. At night under a dim natural colored shades not always just blue - 10% capacity, i can see all. They are realy little rascals at night they interact more then during the day, chasing eachother and even making small jumps in the stream. I can regulate my pump got 40 litre and pump can push 600l/h. If i put it half power they go play in the stream. Seems to be a reflex which can be triggerd.  Even the shrimps like cruising around at night, rather than eating. Plants are resting at night like chain saws and they play or sit togheter on a wavy leave, surfing.

Go to the gray shades
http://www.december.com/html/spec/colorper.html

They are the most beautifull. And then devide the % under the 10% led capacity. Amazing!

Now that i come to think of it.. Maybe it is the sudden change in oxygen level when using high co2 during the day. Which result in different behaivor. Or the Ph fluctioations. Could be a interesting study. We all should make notes and compare. Haha..


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## sciencefiction (27 Apr 2015)

These are my 4 older ones during the day, normal behaviour. Two minutes after the video and a couple of them were gone to other parts of the tank. I don't see them often dosing on one spot for ages or not cleaning up. Some other people's ottos are probably plain lazy  Please excuse the tank state. It's my BBA algae ridden tank.



And it looks like the zebra otto kicked the other otto away from his stone


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## markk (28 Apr 2015)

sciencefiction said:


> Well, then mine have been underfed for 4 years and grown huge being underfed. I think that's not the way to judge things. Mine are quite active during the day although they really shine at night. They play rounds on the glass just like my clown loaches do, chasing each other, nothing to do with food or the lack of it I think.



You're right of course - not the only way to judge it, but as you said later, there are other factors at play such as species, flow, temperature etc.



sciencefiction said:


> These are my 4 older ones during the day, normal behaviour. Two minutes after the video and a couple of them were gone to other parts of the tank. I don't see them often dosing on one spot for ages or not cleaning up. Some other people's ottos are probably plain lazy  Please excuse the tank state. It's my BBA algae ridden tank.



You think you're algae is bad - you should see mine at the moment After a week away with the family, I had some filamentous algae that was 12 inches long - much to my son's amusement. Judging by your video, I would (respectfully) suggest that your ottos have to work much harder to find food whereas mine (all Otocinclus affinis I think - and relatively young) barely need to move to find a new patch to graze on. They also have virtually no competition at the moment, being the only fish in the tank.

Flow in this tank is also relatively high - no spray bar, just the filter outlet directed diagonally across the tank; so unsurprisingly they tend to congregate at the far corner where the flow hits the glass.

I had some success breeding oto's many years ago and the tank was always high flow/high algae - with no supplemental feeding.

regards

Mark


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## sciencefiction (28 Apr 2015)

markk said:


> and relatively young) barely need to move to find a new patch to graze on.



That's my point. They eat all day long. And as far as I know ottos need to eat 24/7 to maintain their digestive balance/bacteria that helps them digest.  If you've happened to buy an emaciated otto like I did, twice I might say, you'd notice they don't move around one bit, sitting on one spot refusing to munch on algae or any veg,  and eventually starve themselves to death.   In my mind an active otto is a healthy otto and mine have done well so far "being active".  They also love playing in the airstone a lot, diving in and out of the bubbles. Also, ottos that spawn chase each other around the tank for hours.

But I would imagine a fish that overfed itself may need a "chill" time to digest all that. It probably applies to ottos too but mine as I said are not inactive during the day. The otto fry that I raised was munching 24/7 around the tank and a year later does exactly the same, eats all day long, light or no light, cleans the glass, plant, leaf litter, stones.. I call them water butterflies.

I've got high flow in both tanks by the way. The first with 4 ottos is at 12x only via filters plus a large airstone. I used to have an additional powerhead and one more filter for 2 years before, way overkill.
The other tank has a flow of 14x.
They certainly don't lack flow and oxygen in my tanks, both have trickle filters as part of the filtration. One is a completely open top. The other has all it's lids staying open permanently, including the lid for the trickle filter which I recently planted as well.


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## dw1305 (28 Apr 2015)

Hi all,





sciencefiction said:


> In my mind an active otto is a healthy otto and mine have done well so far "being active". They also love playing in the airstone a lot, diving in and out of the bubbles. Also, ottos that spawn chase each other around the tank for hours.


I think we may-be at cross-purposes about how we define active. Yours look really good in the video, nice and plump and what I'd consider "normally" active. What they aren't doing is continually swimming around (looking for food). 

That is pretty much how mine behave during the day, although I have much more heavily planted tanks, with large Amazon swords where they might spend extended time periods. 





sciencefiction said:


> If you've happened to buy an emaciated otto like I did, twice I might say, you'd notice they don't move around one bit, sitting on one spot refusing to munch on algae or any veg, and eventually starve themselves to death.


I think once they are just sitting moribund, like the poor things you see in some shops, there is little hope of recovery.

cheers Darrel


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## zozo (29 Apr 2015)

Just for the fun of it..


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