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Thread: Questions on Corydoras

  1. #1
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    Questions on Corydoras

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    I've came across sites saying that by using fine sand or the likes as gravel would be beneficial to their barbels. Someone was actually quoted as saying bigger and rougher gravel actually not good for corys. Is there any truth in the saying?
    Last edited by Quixotic; 21st Sep 2007 at 23:34. Reason: Formatting, split post

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    Barbels are sensory organs of Corydoras, used to search for food from the substrate, and for breeding activities in female Corydoras. They will have trouble feeding if the barbels are worn, and this could also result in secondary infections.

    Therefore, it is best to avoid sharp substrates that can worn out their barbels, and use fine gravel instead.

    However, there is another line of thought that attributes the worn barbels to high nitrate, which is still very much debatable and contentious.

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    That sure made alot of sense Quixotic.Unfortunately i'm not exactly using fine sand like gravel but instead the standard GEX brand soil for my planted set up.
    Hopefully the coarser substrate would not really do much damage to the barbels?
    In all case,i'll keep a close eye and observe behaviour to understand more on these adorable fishes!
    One last question though,my corys frequently dash to the water surface to take quick gulps of air.What seemed "cute" to me in the beginning led to doubts about oxygen content within my tank. Is this behaviour considered normal? Or are their behaviour reflective of oxygen conditions?
    As far as i can see,all fishes do not exhibit any kind of stress. All of them are schooling peacefully together and no squabbles up to date!

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    Now that you mention it, mine also did the same "dash to the water surface to take quick gulps of air". Other fishes seem to be OK, my plant is pearlingso I doubts if it is because of oxygen content, but who know?
    -Robert
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    My Blog: http://aquatic-art.blogspot.com/

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    Quote Originally Posted by aquanatix View Post
    Unfortunately i'm not exactly using fine sand like gravel but instead the standard GEX brand soil for my planted set up.
    Hopefully the coarser substrate would not really do much damage to the barbels?
    To see if the substrate is sharp or otherwise, rub them with your fingers. If the pain is obvious, then it may not be suitable. GEX soil seems to be okay based on my observations straight from the package in the LFS.

    Quote Originally Posted by aquanatix View Post
    One last question though,my corys frequently dash to the water surface to take quick gulps of air.What seemed "cute" to me in the beginning led to doubts about oxygen content within my tank. Is this behaviour considered normal? Or are their behaviour reflective of oxygen conditions?
    If they don't dash to the water surface in say every few minutes, then your tank condition should be fine. This is actually an adaptation in the wild to habitats that lack oxygen. However, they will also do this even under all conditions and for a different purpose - maintenance of hydrostatic balance. So it is perfectly normal and don't need to worry too much.

    From Tree of Life, http://www.tolweb.org/Callichthyidae/15197 (The genus Corydoras are classified under the family Callichthyidae)
    Quote Originally Posted by http://www.tolweb.org
    The callichthyids inhabit a variety of different habitats in the Neotropical region, from small, swift, oxygen-rich creeks to big rivers and flooded areas, including swampy and muddy habitats where oxygen might be virtually absent. To survive in these habitats, callichthyids perform air-breathing. The air is collected at the water surface and swallowed, since their "accessory respiratory organ" is the intestine, and is eventually expelled through the anus. In this family, however, the air swallowed plays a more important role in the maintenance of the hydrostatic balance than in respiration itself, contributing with about 75% of the necessary air for neutral buoyancy (Gee, 1976; Gee & Graham, 197. Additionally, unlike the catfishes in the families Loricariidae and Trichomycteridae that practice aerial respiration only in case of hypoxia, the Callichthyidae breathe air continuously under all water conditions.
    And this is why barbels are important for reproduction.
    Quote Originally Posted by http://www.wikipedia.org"
    A unique form of insemination has been described in Corydoras aeneus. When these fish reproduce, the male will present his abdomen to the female. The female will attach her mouth to the male's genital opening, creating the well-known "T-position" many Corydoras exhibit during courtship. The female will then drink the sperm. The sperm rapidly moves through her intestines and is discharged together with her eggs into a pouch formed by her pelvic fins. The female can then swim away and deposit the pouch somewhere else alone. Because the T-position is exhibited in other species than just C. aeneus, it is likely that this behavior is common in the genus.
    Some good reads here,
    http://en.wikipedia.org/wiki/Callichthyidae
    http://en.wikipedia.org/wiki/Corydoras

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    Hi,
    It is normal for them to dash up for air once a while. I once forgot to switch on the airpump for a few hours after some maintenance/cleaning and those cories started to dash up to the surface for air.

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    Ahhh..tanks for the in depth articles!
    At least now my mind's at ease...learnt to appreciate the schooling behaviour more now!
    Except that my 9 do not exactly school together?
    Maybe i should get a few more?

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    do some cleaning on yout tank and they will schooling together again, at least for a while.
    -Robert
    Aquascaping is a marriage between Art and Farming
    My Blog: http://aquatic-art.blogspot.com/

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    if i'm not wrong not all variants of corydoras school together? besides sterbais and pygmy, any other schooling variants? just to ask, how many cories would you recommend for a 3ft tank?
    -clint- ~apisto keepers unite!~

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    Mine school together when there's food. Otherwise, they just go whereever they want. Almost all of them do that. Well, they do school together when they are placed in a new environment. But after getting used to it, they usually venture out by themselves.

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    They aren't tight schoolers to begin with, which is why I hesitate to use the word school on them. Rather, I would use this description: they enjoy each other's company, with plenty of interactions between each individual. Sometimes you would see individuals following one another around the tank.

    Quote Originally Posted by iwishweallcouldwin View Post
    if i'm not wrong not all variants of corydoras school together? besides sterbais and pygmy, any other schooling variants? just to ask, how many cories would you recommend for a 3ft tank?
    Well, they are distinct species, not variants. Generally, regardless of different species, they do enjoy one another's company, so yes, they "school" togther. However, there are exceptions, e.g. Scleromystax barbatus can be territorial and aggresive sometimes, so they may not be suitable to be mixed with other species.

    And IME, sometimes size do matter, so I don't recommend mixing those that have huge differences in sizes, for example C. sterbai and C. pygmaeus. When doing so, I find the pygmy cories not doing very well, for reasons unknown (possibly outcompeted for food?).

    For a 3 feet tank, depends on your tank stup, current bioload, and the species that you intend to keep. For pgymy cories, you can easily have a few dozen of them.

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    Shoal will be a better word if you are looking to describe their behaviour.
    ~ Vincent ~ Fishes calm your mind...
    http://www.flickr.com/photos/valice/





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    i agree totally that species, not variants, of significant size differences should not be mixed together, thanks quixotic and valice for your input and correction, now that you say that, it does occur to me that your descriptions of the corydoras' behaviour is indeed more accurate. they are highly interactive catfishes, and they never fail to amaze me with their behaviour. fell in love with them instantly after seeing a bunch of sterbais shoaling around in my friend's tank.
    -clint- ~apisto keepers unite!~

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    Now that i've read everyone's input regarding cory behaviour i reallized that my pgmy corys did school together during the initial week in my tank.After which they gradually just went around in smaller groups of 2 or 3. I did find their behavious strange but after reading everyone's view here seems like they should be doing ok?
    Thanks for the valuable input guys! Need to familiarize myself with corys more as i'm still new to the species. Wish me luck!

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    Quote Originally Posted by Quixotic View Post
    And IME, sometimes size do matter, so I don't recommend mixing those that have huge differences in sizes, for example C. sterbai and C. pygmaeus. When doing so, I find the pygmy cories not doing very well, for reasons unknown (possibly outcompeted for food?).
    I do have 2 generations of C. sterbai and C. pygmaeus in a 3 ft tank and they seem happy :-) Maybe the sterbai i have are "gentle" despite their size.

    The sterbai hang-out at the substrate and the pygmy, mid water / hanging out over leaves e.g. java fern etc.. and i definitely see the pygmy cories more often with the "shoaling" behavior; 4 - 6 of them over one java fern.

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    hi youjin, when you say 2 generations, are you implying that you bred them before? how many cories do you have exactly in your 3ft?
    -clint- ~apisto keepers unite!~

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    there are originally x 6 c. pygmy and x 6 c. sterbai more than a year ago. As last week, counted x 10 pygmy and x 8 sterbai (there could be more, i hope).

    No, i did not deliberately bred them. Let nature takes its course ? There are espei rasbora and rummynose in the same heavily planted tank (look more like a jungle) :-)

    Thanks ! I am learning so much reading all your threads....
    Last edited by Youjin; 26th Sep 2007 at 23:50.

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    Corydoras will spawn in your tank if the conditions are right, and some fries may survive if there is enough plant cover for hiding. I would say that their chances of survival are also much higher in very matured tanks.

    luenny have some accidental fries and so have I, a C. davidsandsi fry and another which I think is a hybrid fry.

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    Haha wow this is very very interesting indeed. A hybrid fry must be pretty cool. What then are the right conditions may i ask?
    -clint- ~apisto keepers unite!~

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    The right conditions are when they feel like it. Honestly, you can have them in your tank for ages with good water quality, variety of good food etc and yet, they aren't interested in doing anything.

    But lower temperature, soft water and subdued lighting will generally be conducive. This is what those who intend to breed them on purpose do, lower the pH and perform large water change to lower the temperature.

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