# Other Aquarium Forums > Freshwater Fauna > Catfishes >  Differences between Otocinclus affinis and Otocinclus vittatus?

## uklau

> Usually they have _Otocinclus affinis_ or _Otocinclus vittatus_.
> 
> Cheers,


How to differentiate between the two? Thanks.

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## Quixotic

uklau, I have split your post out from here, http://www.aquaticquotient.com/forum...ad.php?t=29154, as I feel that this should be a thread on its own, instead of being discussed in the Invertebrates section.

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## Quixotic

I did a little research, and this is probably the method that can be relied on.

From PlanetCatfish, it is mentioned that there are 3 keys to determine if the _Otocinclus_ is _O. affinis_.

1. golden sheen
2. very narrow lateral band
3. iris diverticulum

Let's take the picture from AQ gallery taken by V31 as an example.



It doesn't seem to have a golden sheen and the lateral band looks rather wide. However, as I am not sure what/where exactly is the iris diverticulum, I can't verify key # 3.

Regardless, it doesn't seem to match 2 of the keys, so there is a high possibility that it is not an _O. affinis_. Comparing with the actual picture of _O. affinis_ seems to point to this as well.

The only two known pictures of the actual _O. affinis_ (according to PCF)
http://www.otocinclus.de/affinis.htm
http://www.planetcatfish.com/catelog...pecies_id=1083

The actual discussion on _O. affinis_ on PCF is here,
http://www.planetcatfish.com/forum/v...05df725316899f

As for _O. vittatus_, not much is known yet. Until then...

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## uklau

Thanks, Quixotic. Very much appreciate your help  :Jump for joy:  .

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## ranmasatome

It can be seen from the picture that this one got no iris diverticulum

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## Quixotic

Voila! No iris diverticulum = not _O. affinis_. Iris diverticulum is present on _O. affinis_.

But I still don't exactly know for sure what the heck is the iris diverticulum. Hahahaha...

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## valice

If I am not wrong, this is the iris diverticulum.


But the picture one shows that of a L128.

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## ranmasatome

valice so smart hor... :Grin: ...

i did try to describe this to you in the other thread ya??

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## Quixotic

Thanks valice for the enlightenment! Heehee...

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## illumnae

is there any difference in keeping these 2 different species of otos besides the slight differences in looks, such as one being easier to keep alive or having particular character quirks?

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## Quixotic

Character quirks? I think that would be up to individual fish, no?  :Grin: 

There are not much differences in general requirements, there are almost the same, pH, temperature, food etc. But _O. affinis_ is probably larger, listed as 5cm SL while _O. vittatus_ is listed as 3cm SL.

However, considering the lack of information on the real _O. affinis_, and propensity of confusing _O. vittatus_ with _O. affinis_, finding _O. affinis_ in our LFS would be considered a great catch.  :Razz:

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## illumnae

i saw _O. affinis_ labelled in biotope and _O. vittatus_ in polyart...was deciding whether there was a difference before buying a few to replace my albino BNs in my apisto tank =)

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