# why are otos considered weak?



## dude26212 (Dec 2, 2010)

ok so i have experience with two batches of otos. the first time i had two when i was just starting to try and get into the hobby. i planted the plants, waited, and added the two otos, waited a lil longer and tried to get some guppys. for some reason the guppys kept diein on me, after about the 4th exchange at petsmart i decided that maybe the declor i was useing may have gone bad (was old from when the family use to have an aquarium and didnt know it could go bad) switched it up and tada guppys live and the otos now had some take mates. fast foward a few years and i decided to start my hobby back up in a new house. i get the plants, plenty of fish (including 3 otos) and start feeling good about it till ick strikes the tank and kills all the fish off except a single oto. figure its only time till he is killed off so i just leave him to his devices and let the tank loose on itself only topping off water. well this evening i decided to start taring down the tank so i can see what plants can be salvaged and to clear a space to a quarentine tank and lo and behold the lil oto is still kicking after a few months of tank negligence. so in my experience otos seem to be the hardiest fish ive owned so im curious why i feel like ive read a bunch of stuff on how easily they seem to die off?

and yes i know wall'o text, spelling, grammer and what not but if i tried to fix it (which would probably involve googling the rules for fixing it) i would just get frustrated and not even bother posting.


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## Tugg (Jul 28, 2013)

Otos have about a 50% death rate coming home from the store for the first 30-45 days. They are mostly wild caught and go threw hell getting to our homes. Its hearsay, but ive read they dont actually digest their food. Gut fauna breaks down the algea and they eat the byproducts. If that bacteria is lost in the capture/shipping/LFS period they are given a death sentance and no matter how much they eat, will slowly starve. If they live past that, they don't seem to die. They just vanish from time to time.

Being neglected probably made for a nice stress free home.


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## dude26212 (Dec 2, 2010)

allright so as long as you get one that has a chance of liveing they become tough lil buggers?


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## Darkcobra (Nov 23, 2009)

Of the common pet store fish that I've kept, otos are one of the two I've found are particularly sensitive to rapid changes in water conditions, especially _salinity_. (Neon tetras are the other.)

Aquarium salt is often used as a general disease preventative in stores. If you float the bag in your tank to equalize temperature, then dump them directly into your unsalted water, it causes stress. On top of other stresses they've already recently suffered - as well as typically being malnourished - this can cause immediate death by shock, or onset of disease and delayed death; and the overall high death rates that many consider normal for this species.

While simply buying from stores that don't use salt will improve survival rates, that may not always be an option. Introducing them to your water with a long drip acclimation seems to be the best practice. With at least a two hour drip, I get near 100% survival rate.

Then follow up by feeding them well. Many are finicky eaters, especially at the beginning, so variety is important. I make sure whatever tank they're initially introduced to (typically a quarantine) is heavily planted, so there's always some natural food present. Then supplement with small amounts of a variety of foods. One day they'll get shelled frozen peas. The next, algae chips. And the day after that, whatever staple food they will be most likely to find in the tank and environment they're eventually headed for (typically a high quality flake). Something in that menu will initially tempt their palette and get them to eat heartily, keeping them nourished while they experiment with and grow accustomed to other items. Making sure they aren't spooked away from food by more boisterous fish during this period helps as well.

Once fattened up and with no history of recent stress, they are indeed tough little buggers. I can then treat them like any other fish, moving them between my own tanks without special procedures, even if the water parameters are quite different; so long as moves into or out of brackish water aren't involved. The occasional shelled pea or algae chip is still a nice treat, there are many benefits to macrobiotic diets.

I haven't heard [Tugg]'s suggestion before, that they may lose intestinal flora and be unable to process foods. In mixed species quarantine, I've occasionally been required to subject them to some rather harsh antibiotic cocktails in order to deal with issues with other fish. So if this loss of bacteria does occur, I feel that given an appropriate diet, conditions, and time, this is a survivable event and the flora can re-establish themselves.


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## Tugg (Jul 28, 2013)

Like I said, the gut fauna theory was hearsay (something some other guy wrote on a site), not a scientific paper or anything exceptionally creditable.

http://www.fishlore.com/fishforum/otocinclus/138805-my-otocinclus-catfish-died.html


CatfishJack said:


> ...Stress leads to them not eating, not eating leads to the active bacteria in their gut dying out, and with out these bacteria the Oto has a hard time digesting food. Often times new Otos die of starvation, and it seems it happens even after you witness them eat, because the bacteria is gone and they can't digest and process the food...
> 
> ...Due to the way their digestion works if those gut bacteria are dead they can eat food but cant process it, so they basically starve...


An article he refrenced that I missed the first time does add a little credibility. This article also mentions that they can share the guy bacteria, so perhaps this is another reason they do better in larger groups.
http://www.skepticalaquarist.com/otocinclus


> ...no vertebrate vegetarian can digest cellulose, not one! so each carries a species-specific community of anaerobic bacteria (and some protozoans) that do the work. Ruminants even have a special fore-stomach (the rumen) where grass is fermented in a rich bacterial soup, protected from stomach acids. Dairy cows are nourished, not so much by grass, but by bacterial by-products, which include some vitamins, and by digesting some bacteria: cow breath! Now, look at the size of the Oto. Scarcely room for a billion gut bacteria in there to do the work, eh? Starved Otos in transit can lose so much of their gut bacteria that the internal ecosystem doesn't revive- even with a glut of tasty algae in your tank! It just passes through their system, like when you were too hasty eating that corn-on-the-cob, remember? Not much nutrition when the kernels passed right through, because your system couldn't digest them open. Otos need a jungley tank with lots of leaf surfaces to run over. (If you can count your Otos, you haven't got enough plants.) But the vegetable supplement we give them (zucchini, spinach, etc.) has to be constant, or else they won't have the gut bacteria to process the green treat when it finally does arrive. Hopefully with your algae, and plenty of natural green cover, and your constant feedings of spirulina flakes or algae wafers plus veggies every few days,and perhaps sharing the gut bacteria of Otos already established, Otos that aren't too far gone should come round and thrive with you.


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## Darkcobra (Nov 23, 2009)

Thanks for the link, I read it and found it interesting.

It sounds feasible. Although most of the nutritional energy in grass leaves is in the form of cellulose, so I'm not sure if the comparison the article makes is exactly applicable. Our otos probably have a better and less restrictive diet than cows.  It seems as if they can at least subsist on bacterial biofilms alone, although that's certainly not optimal.

Plus unlike grass, some algae produce cellulases, enzymes that break down cellulose into sugars. Not sure if conditions are right in their gut to allow that to occur, but it could be of some assistance.

Regardless of what's happening behind the scenes, proper care and feeding is still the same. And they are certainly happier - and more entertaining - in groups as well!


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## AaronT (Apr 26, 2004)

It has to do with how they are treated during importation. I forget what it is exactly, but there is something that kills them off slowly if they are not treated for it. I've always had good luck with the ones from www.msjinkzd.com.


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## JanS (Apr 14, 2004)

I've never had good luck with them either out of all of the fish I keep so I don't get them anymore. I'm sure a big factor are the reasons stated above.


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## UDGags (Oct 4, 2011)

I've had good luck with the Oto's I've gotten from Wet Spot


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## asukawashere (Mar 11, 2009)

If there's any truth to the gut flora theory, I wonder if offering probiotic foods like Cobalt makes would have any effect on survival rate. Might be something for someone to try sometime...


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