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Hi,

I have 5 Cory Sterbai and 6 Otos (at least 2 species, I'm unsure which exactly) that during the last four months or so have become increasingly shy.

The corys have gone from happy aquarium clowns, that played all day if full view, to invisible recluses. If they happen to be in the open and a person gets within 3 meters (10 feet) of the tank, they bolt to "safety" and hide in the plants. The otos used to munch algae on all sides of the aquarium and on the plants/decor - now they are nowhere to be seen during the day.

At night, both corys and otos come out and play in the filter outflow current and in the air bubbles. But if I get near they panic and run as soon as they can see me.

They did not change their personality suddenly, there has been a slow change over several months.

I would much appreciate any help in identifying the problem!

1. Water parameters
a) Temperature range: around 26 C (~79 F)
b) pH: around 6.8
c) GH: 9
d) KH: 5
e)Ammonia, Nitrate, Nitrite, levels: ammonia, nitrite practically zero, nitrate varies 25-40 ppm
f) Water change frequency: 50% weekly

2. Tank set up
a) Size: 12g
b) Substrate: ADA Amazonia New Powder in the back, sand in front
c) Filtration: Eheim 2074
d) Furnishings: plants, a few stones
e) Other tank mates: snails
f) How long has it been set-up: version 1, since February; current version, since 3 weeks ago

3. Symptoms / Problem description
All my catfish are hiding all day long. Believe it or not, there are 11 fish in this pic:


4. Action taken (if any)
My previous setup had gravel instead of sand - I didn't realize initially that it's not good for the corys. I thought that's why my corys were becoming more shy. So about 3 weeks ago I reset my tank completely and replaced all the substrate with fine-grained. There was no positive effect, they just continued to become more and more shy.

5. Medications used (if any)
No medication.

I'd say that's pretty natural/normal. They will probably get better with time. Adding more places where they can hide (and adding a dark background to the tank) probably also help.

--
Mats

This is not going to help much, but I've always considered otos and corys to be (very) shy. And although your tank seems quite open and light, I can't recommend a tank that's full of hiding places and dark, for that is what my tanks usually look like.
In my experience C. sterbai is the most reclusive/shy species I've ever kept, with or without dither fishes. And for the exact above reason I no longer keep these fishes, as my main inhabitants (Auchenipteridae) are already pretty shy (= nocturnal).
Possible cause: they are quite sensitive to sounds/noise. Did anything in that respect change over the last few months?

Hi florini,

I have basically the same experience with my c.duplicareus. They were fine (quite active and all around the tank) when I brought them home and it it was like that for couple of month. Then something happened and I could very rarely see them during the day. They were hiding in darkest spots of the tank (under filter, behind the bog wood. I wasn't happy about this so recently I moved them to another tank and set it up so that the only places where the shade are well visible from the front so that at least I can see them. I didn't provide them so much cover in general so that not every fish can hide at the same time. I think this is slowly turning their behavior back and they are no more so sensitive to any movement around the tank and go for food during the day as well which I didn't see before. My tank is not so bright like your one seems to be though. I also had one c.venezuelanus which I originally placed with very active pandas and this guy was also very active. Not sure if it was it's natural behavior but I was very happy about this fish. Then I moved pandas elsewhere and put duplicareus guys to his fellows. Not a good move - venezuelanus quickly adopted their hiding behavior and I couldn't see him during the day anymore. Now he's back with pandas and it's getting better again.
Based on my experience I wouldn't recommend adding more hiding places unless you put them where you can still see the fish if it hides there to keep both you and fish happy. Adding floating plants or "darker" plants like cryptocoryne should help. Behavior also changes with age but this is not your case I guess. You may try to add more active fish but this may not work if group of sterbais is big enough. BTW - as far as I know c.sterbai is one of the least active cory on top of being shy/reclusive.

I'm a bit surprised about your otos. My experience is different to what Marc says. I consider them to be basically careless to what is going on around the tank.

Your tank is crying out for a shoal of lemon tetras

And I would add additional strong current - play around with where you direct the current. In my experience that works with corys every time. The tetras would shoal in the current... eau naturelle. Pardon ma francais!

Thanks all for the comments and advice.

Mats, I'll try adding a dark background to the tank. In my opinion they already have enough places to hide (see the photo in my first post - the fish are hiding well enough, right? ).

Marc, no, noise level did not change since I have the aquarium, it's neither louder nor quieter. The tank is in the living room where it's usually a lowish amount of noise when people are around, with the occasional peak when we watch a loud movie or we have kids visiting, but that's how it's been from the beginning.

Vlacek, good to know my experience isn't unique. If sterbai are among the shyest, which are the most active and fearless cory species?

wrasse, you mean the tetras as dither fish or just for their good looks?

Also, what do you mean about the current? If I change it the corys will come out of hiding?

florini wrote: Vlacek, good to know my experience isn't unique. If sterbai are among the shyest, which are the most active and fearless cory species?

This is a good question but I don't consider myself experienced cory keeper to answer as I only had a few species. Panda would definitely be on top of my list. I'm trying to find a good and more unusual active replacement for pandas but no luck yet. C.venezuelanus I have looks promising but I shouldn't be deducting from just one fish behavior. Shame I can't get hold of more of them anywhere near at the moment.

I wonder what others will suggest as active and fearless species to try.

florini wrote:wrasse, you mean the tetras as dither fish or just for their good looks?

Also, what do you mean about the current? If I change it the corys will come out of hiding?

- I mean both... Your tank is nicely planted and subtle-coloured tetras would compliment it.

- Try directing the filter outflow down the back of the tank, if it's strong enough you might find the corys will settle at the front.

- In your photo it looks like dark sand behind the rocks, pale sand at the front. It looks nice but if all else fails this might be what the corys aren't happy with.

Greetings. In my experience, trying to label a species as "shy" simply does not hold uniformly true among groups of fish within a species. Simple things like the amount of light, degree and direction of current, type and location of cover, tank mates, weather conditions, physical location of the tank and foot traffic are some of the more common things which can have a effect on how any group of fish behaves, on any given day. Fluctuations in water parameters can also affect the behavior of any group of fish.

Over the years, I have been surprised to see so many people list C. sterbai as one of the problematic species, in this regard, as I have 3 groups of them. all of which are far and away some of most non-shy groups in my fish room. Two groups in 10 USG, dimly lit tanks and a large group in a very well lit 55 USG. The former are always visible, but not very active during the day. The latter are constantly shoaling back and forth in a tight group. While there is substantial cover, they rarely use it and are almost always in plain view.

I used to have a problem with never seeing certain groups of fish. I lowered the light intensity and provided floating cover over approximately one-third of the water surface. This resulted in a dramatic difference in the behavior of most groups. My C. gracils, which I would have classified as an extremely shy species before the changes, are now front and center and reasonably active during the day. That being said, there are periods where I might not see them for a day or two and just as suddenly as they disappeared, they're right back to their less shy behavior.

Labeling a species as "shy" or "never visible" can only dissuade our fellow fish keepers from trying a species that they may be very interested in keeping, from doing so. I totally disregard any supposed difficulty in keeping any Cory. There is no harm in obtaining said species and seeing for yourself if they are as problematic as rumored. Just like you bought them - you can always sell them, if they don't meet your requirements. Keep in mind that we should not be keeping Corys for them to entertain us. If, after trying different set-ups, they still do not meet your visibility threshold, you must simply choose to move them out, or accept them as they are with the understanding that if the fish are eating, healthy and even spawning - then enjoy seeing them when you do and leave them alone when you don't.

If I had paid attention to all I have heard and read over the years about the supposed difficulty in keeping certain Corys, I would not have many of the beautiful species that I am fortunate enough to keep.

I would encourage any hobbyist to keep any fish that you like (if you can meet it's basic requirements) and see for yourself how they react to your particular set up. Try a few variations until you find something that works. If in the end, you feel that you are unsuccessful, sell them or pass them on to a friend, but don't label them "hard to keep." Better to say, "I had problems keeping them, but that does not mean that you will."

I have had good luck with species that many consider difficult and very poor luck with species labeled as "easy." There is no, "one size fits all."

Just my 2¢.

Cheers. - Frank

P.S. I have a 20 USG "L" with 24 zebra otos. You can't walk up to that tank and not see almost all of those fish in plain sight. They are always hopping around the driftwood twigs. A very cool, little fish and my next spawning project.

Here is how my young Corydoras sterbai behaved when I placed a 100 in a 75 gal.

Coryologist wrote: Labeling a species as "shy" or "never visible" can only dissuade our fellow fish keepers from trying a species that they may be very interested in keeping, from doing so.

I've reread the whole thread and afaics no-one is talking other people out of keeping Corys (or other species).
I understand your concern, but imo one member has a remark/question which is (more or less) confirmed by other members.
That has nothing to do with dissuading, but just giving one's opinion.

Marc van Arc wrote:I've reread the whole thread and afaics no-one is talking other people out of keeping Corys (or other species).

Right. The key word in the sentence is "can." I stand my my contention. - Frank

P.S. Improper use of language on my part. I should have used the word, "may," instead of "can." Of course it "can." That doesn't mean that it will. But, it surely may. lol.

Coryologist wrote:I stand my contention. - Frank

You may

MatsP wrote:adding a dark background to the tank

That did the trick. I added a black background and their behavior changed overnight. They now act exactly as they did when I bought them - they stay out in plain view. They don't play or chase around much (they just sit on their bellies 80% of the time) but at least they don't run to the woods when I get closer than 2 meters from the tank.

Thanks for the suggestion.

Florin

It doesn't solve any shyness problems but I highly recommend using small Peckoltia or Hypancistrus species as the bottom feeders in Discus tanks for several reasons. Two exceptions would be L260 and H. zebra which I feel are best set up in species tanks.
These genera of plecos and Discus both thrive on the same foods. Plecos are shier than most Corydoras but they soon adapt to the daily feeding schedule of Discus. This mainly pertains to Discus and not necessarily most tanks.
1. They feed mainly on the bottom and on other furnishings in the tank.
2. One adult pleco can eat as much as four or five Corydoras.
3. They both do best when kept at about 84*F/34.4*C.

It is possible to have a good size Cherry Shrimp colony with the L260 and H. zebra for some added action, color and they clean algae and food scraps off plants if you use any. I normally have a potted Sword plant or Cryocoryne. I also usually use Hornwort or Najas which are free floating and provide shade and more surface areas for shrimp. I think growing plants have a positive effect on water quality, too.

PS Forgot to mention, the behavior of the otos did not change with the black background. They are still extremely shy. They are invisible during the day. If I stalk the tank after lights out I *may* catch sometimes a glimpse of an oto, but it bolts away as soon as I make the slightest move. I cannot vouch I still have 6 of them - I wasn't able to count them for months.

I had very similar problem. I keep group of 10 C. Habrosus and 7 O.Macrospilus with 4 heterocharax sp. Corys started to hide all day under bogwood. I put some black sand in, but it didn't help. Now I'm starving them. They have had to forgot how it's to be hungry and now by reminding them I motivated them to go out and search - so they do. I do monitor their health but try to give them 3rd what they used to get and they are far more active. It doesn't work with otoses, simply because I@m scared to starve them to death as they cannot compete for food even with apple snails..

When I first got each one of my Cory's they were very playful, but as they got older they do hide almost all the time. At first it confused me till I read up on the way these fish live in nature, they are pretty laid back compared to most fish. At night I can't catch a glimpse of them playing and dancing knowing no one is watching them (so they think) which is also why I always feed them at night so that the food dosent go to waste during the day when they're all huddled up. This is very normal for catfish which is why I would love to get more, they are so beautiful in their own way!

Hi all,
I think mature Otocinclus are largely nocturnal. I very rarely see any of mine during the day, but at night they are much more active. I keep extremely weedy and complex tanks, so it isn't a cover issue.

I have Corydoras pygmaeus and C. hastatus in a tank with Marbled hatchets and a variety of shrimps. The C. pygmaeus are very active and visible during the day, but I almost never see the C. hastatus. If I do see them it is one or two individuals swimming with C.pygmaeus after I have fed Grindal worms.

cheers Darrel

My bronze cories, no matter the number (they are currently 20 strong in a 90 gallon), seem prone to flights any time I go near the tank. Now with the hoplos around them, I've seen the RUN tendencies go down.

On the other hand, my concolor cories are always out and about.

My tank is a 10g jungle. I have black sand, a dark background and lots of floating plants.
My C. habrosus (5) are super active, always checking things out.
My Otos (2) are out and about. They used to startle more, now they are pretty calm.
I have Celestial Pearl Danios - they can be shy. Mine do hide, but the swim out front plenty, esp. during feeding time.

I do trim my plants but they grow so fast I have to trim weekly and the fish seem to like it as it is.

The FTS was taken before a trim

To the best of my knowledge neither otos nor corys are particularly nocturnal animals. Certainly all I've had seemed to be active during the day.

I second the suggestion to put some sort of free-swimming fish in the aquarium - some small tetras, or pehaps guppies, it doesn't really matter what as long as they're outgoing and active. I suspect dithers like that would do wonders for the shyness of your fish.

Another thing is to learn the fish to associate "the big shadow outside the glass" with food: give a little pinch of food every time you walk up to the aquarium. Most fish will quickly associate your visits with feeding, and act accordingly.

Also check the fish for visible signs of disease. Some diseases, like for instance costia, make fish very shy and skittish.

EDIT: Danio margaritatus and the close relative Danio erythromicron are fairly atypical danios, in that they're shy and spend most of their time sneaking around among the vegetation; most other Danio are outgoing to the point of being hyperactive and boisterous.

You may want to try feeding your Otos Repashy Superfoods Soilent green. Drop it right in front. My Otos love it, they are also on the shy side but that always works! When I feed it I found a third smaller Oto I didn't even know that I had!