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A good article on corydoras..

Discussion in 'Catfish' started by gupman, Nov 18, 2007.

  1. gupman

    gupman AC Members

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    Common Corydoradine Catfish

    (Helmet Skin Catfish)

    First Edition

    A guide to the care, feeding, breeding and raising

    Common Corydoras Species

    By James Studdart BSc (Hons)


    -About Corydoras

    - Corys at home
    -The Tank Setup
    -Company of their own
    - Tank mates
    - The Tank
    - Planted Cory Tank
    -Common Species Identification
    - C. Aeneus (Bronze Cory)
    - C. Sterbai (Sterbai's Cory)
    - C. Paleatus (Peppered Cory)
    - C. Trilineatus (Three Line Cory)
    - The Albino Cory: Not a single species
    - Sexing
    - Preparation
    -From Eggs to Fry
    - Eggs
    - What to do when you get eggs
    - Tank Setup
    - Fry
    - Tank Setup
    - Micro Worms
    - Pre-made foods
    - Growing out


    I would like to thank the following people for their help, and their generosity.
    My thanks go directly to planetcatfish.com for granting permission for the use of
    their website for information, and the use of their images.
    The following people and organisations are also to be thanked:

    Tropical Fish Forums – www.fishforums.net

    Inchworm of Tropical Fish Forums

    Carmen Webb – for providing the Microworm Article, photos and my
    starter culture
    And any other people who I have not mentioned here but helped me in my quest
    to produce this documentation.

    About Corydoras

    These fish are members of a South American catfish genus known as Corydoras.
    Corydora are freshwater temperate and tropical catfish in the armoured catfish
    family, and are commonly referred to as Corys. The type species for this genus is
    Corydoras Geoffrey. The name Corydoras is derived from the Greek kory
    (helmet) and doras (skin).

    Corydoras is has over 180 described species, many variants exist as well,
    including colour morphs and long fins varieties, plus several hundred Corydoras
    species are not yet classified, but kept by aquarists. These species are given C-
    Numbers, similar to the L numbers given the Plecs. The C-Number
    categorisation was originally devised by Hans-Georg Evers for the German fish
    keeping magazine DATZ in 1993. As of 2006, there are 153 C-numbers
    assigned, of which 32 have subsequently been assigned appropriate scientific


    Corydoras are native to slow-moving and almost still streams and small rivers of
    South America where the water is shallow and very clear. The preferred bottom
    seems to be sand or sand mixed with mud, sometimes covered with detritus or
    dead leaves. The banks and sides of the streams are covered with a dense
    growth of plants, and this is where the Corys are found. They inhabit a wide
    variety of water types but tend they are documented to prefer soft, neutral to
    slightly acidic water.
    They can tolerate only a small amount of salt (some species tolerate none at all),
    although it is not recommended to add salt to their water. Many species are
    found in schools or aggregations of hundreds or even thousands of individuals,
    usually of a single species, but occasionally with other species mixed in.

    Their main food sources are normally, bottom-dwelling insects and insect larvae
    and various worms, they also consume some vegetable matter. Corydora were
    once thought to kill other tank mates and then feed upon them, although this is
    now known to be a false view. Corydora are not piscivoures, although they will
    eat dead fish, that the find.
    They feed buy sifting through the substrate, using their barbels to taste, with their
    snouts fully submerged in the substrate. This is why you should not use gravel as
    substrate for a tank with Corys, as they will wear down their barbels, which
    causes problems for the fish, and leaves it open to infection.

    Scientific classification
    Class: Actinopterygii
    Order: Siluriformes
    Family: Callichthyidae
    Genus: Corydoras

    Corys At home

    Corys are popular aquarium fish and typically measure around four to seven
    centimetres in length. They are well suited to tropical freshwater community
    aquariums, as they get along well with other species and are not at all
    aggressive. Corys are shy fish and it is recommended to keep them in groups of
    at least six as most species seem to form shoals in the aquaria.

    These are easy fish to keep, being peaceful, small, hardy, active, and
    entertaining. Occasionally they will swim to the surface of the tank, to gulp air,
    they are not breathing the atmospheric air, like beta's and gourami, but they use
    the air to help their digestion.

    Corydoras are very good choices for a community aquarium, and are widely kept
    throughout the world. These fish have a long lifespan; A C. Aeneus is said to
    have for lived 27 years in captivity, although 20 years is not too uncommon.

    There are four species commonly found in aquarium retailers, which we will
    discuss in this article, these are:

    - C. Aeneus (Bronze Cory)
    - C. Sterbai (Sterbai's Cory)
    - C. Paleatus (Peppered Cory)
    - C. Trilineatus (Three Line Cory)
    Some of these species are also available in albino form (See The Albino Cory:
    Not a single species, Pg. X) and Long fin varieties.
    Unfortunately these fish are just one of thousands of species to be involved in the
    act of dying, this is a process with fish are artificially coloured. the latest trend is
    known as "Tattooing" where fish are available with comments such as "I LOVE
    YOU!" and such on their flanks. This is painful for the fish and can also harm the
    fish physically as well as mentally.
    Many retailers have signed up to Practical Fish Keeping's movement to stop this
    act, and there have been laws passed to stop this in the UK and many other
    countries, although the import of dyed fish is still not outlawed, and in the eyes of
    many fish keepers, professional, amateur and beginner should be stopped with
    immediate effect, so please if you see a dyed fish (See Figure 1.0), not just corys
    do not buy them, if their is no demand for them the companies doing this wont
    produce them any more.

    Figure 1.0 - Artificially Dyed Corydora Aeneus

    There are a number of species of other South American Catfish that is commonly
    mistaken for Corydoras, there are:

    - Aspidoras
    - Brochis
    - Scleromystax
    They are very similar to Corydora, although these tend to grow a lot larger than
    Corydoras, there are other distinguishing features with the other species that
    defines them as such, but this document will concentrate on only Corydoras.

    The Tank Setup

    Company of their own

    As said earlier Corydoras do best in groups, they can be kept in groups of mixed
    species, but they prefer the company of their own.
    I shoal of 6 or more is usually suggested by many aquarists, although some have
    managed to keep and spawn them in groups of as small as two.
    Corydoras are peaceful fish, as well as very shy, keeping them in a group will
    help their confidence as well.

    Tank mates

    When considering tank mates for your Corydoras you will not want any
    boisterous fish, such as sharks or Cichlids, nor should they be kept with too
    many other bottom-dwelling fish, as this could cause too much competition for
    food, and being a shy fish, the Corys would probably retreat when challenged by
    another fish, and therefore starve.
    Suitable tank mates include small loaches, such as the Chain Loach
    (Yasuhikotakia Sidthimunki, formerly Botia Sidthimunki), Tetras, such as neons
    (Paracheirodon innesi), Xray (Pristella maxillaris), black phantom
    (Megalamphodus megalopterus) or caridnal (Paracheirodon axelrodi). You will
    find other species such as small plec species will also fair well with Corydoras.
    Basically any small, non-aggressive or boisterous fish would suit a Corydora

    If you are looking at breeding your Corydoras I personally would suggest a
    species tank, although some species will readily spawn in a community tank. In
    the community the eggs are hard to find, and will also be eaten by other fish.

    The Tank

    With all bottom-dwelling fish it is the foot print of the tank not the height tank that
    is important, so the large the foot print the move fish. Corydoras do not create
    vast amounts of waste, like that seen from bristlenose plecs for instance, so light
    filtration will be fine.
    Substrate should be sand, to enable the Corydoras to forage without damaging
    their barbels.
    You can safely keep a shoal of eight, fully grown, Corydora in a 15 gallon (17 US
    gallon) tank, with the dimensions of 24" x 12" x 14" (See below for the tank
    As for decorations, bog wood, monapi wood or large rounded river stones would
    suit best giving the aesthetic look of a natural environment. Ensure you have
    soaked you wood, both bog and monapi leech tannin into the water, this
    discolours the water as well as effects the PH, as the tannin is acidic. Also make
    sure the stones you use do not contain any minerals such as lime, to test this you
    can place a few drops of malt vinegar on the stones, if they fizz they are
    unsuitable, but if you purchased them from a aquatics shop they should be ok to
    As for lighting, standard tank lighting will be fine, unless you are considering
    plants, then you will need brighter and more efficient lighting.

    Tank Specifications:

    Dimensions: 61 x 30 x 36cm/24" x 12" x 14"
    Surface area: 0.18 sqm/1.94 sq ft/ inches sq in
    Volume: 66 l./15 gal. (17.44 US gal.)
    Probable volume: 59 l./14 gal. (16 US gal.)
    Stocking density: 14"/36cm (built up gradually)
    Maximum density: 28"/71cm (theoretical maximum)

    (Specification provided by www.practicalfishkeeping.co.uk)

    Planted Cory Tanks

    If you want to try a planted Cory tank, you will be better advised to you large
    leaves plants such as the Amazon Swords (Echinodorus amazonicus) and other
    such plants. You do not want to use a plant that will cover the floor of the tank, as
    this is irritate your Corys, and they will not be able forage efficiently causing
    unrequited stress. Large leaved plants also give the Corys some place to stick
    their eggs to when spawning, although most of the eggs will be probably placed
    in the glass.
    Keep in mind NOT ALL Corys spawn in this way.
    If you do decide to breed you Corys in a planted tank, you will find it hard to find
    the eggs, and removal is even harder.


    Corydora are omnivores, which means they feed on both plant and animal
    matter, they do require protein, which is more often than not over looked by the
    aquarist, who on some occasions treat them as 'Cleaning' fish. It is true these
    fish are scavengers, but they have more nutritional needs than just scraps that
    are not eaten by the other fish.
    Corys will take any foods, from dried flake food and catfish pellets to bloodworm
    and other insects, frozen or other wise. You can buy freeze dried bloodworm and
    tubiflex worms, but I would advise against using these, mainly because they have
    lost most of their nutritional values, and float, so the Corys wont eat them. They
    then break down and ad to the waste in the tank, thus increase the nitrate, nitrite
    and ammonia levels in the water.
    Although feeding living and frozen bloodworm and such like insects is great for
    the fish, you should only feed these to them every other day, and supplement
    their diets with vegetable matter. On alternative days feed them dried pellets or
    tablets, such asTetra: Tabimin, or King British: Cat Fish pellets. A well balanced
    and varied diet is key to the health and longevity of any fish.

    Figure 3.0 - Suggest Food for Corydoras


    You can buy live foods from aquatic shops, but it is cheaper to grow your own
    cultures of live foods. Either that or buy frozen foods, which now come in handy
    blister packs, with a single serving providing enough food for at least 3- 4 tanks
    of Corys.
    Live cultures for bloodworm are hard to maintain, as bloodworm is the larval
    stage of midges, a small flying insect. You have to maintain a population of
    adults to lay their eggs and hatch them into the worms. In my opinion it is a lot
    cheaper and easier to buy frozen bloodworms.

    Common Species Identification

    The following Section will help to identify your Corydora, as many of the species
    get confused with each other. Some other following have different colour morphs,
    and fin shapes, the ‘normal’ strain are shown here, for the albino strains please
    see The Albino Cory: Not a single species.

    Corydoras Aeneus
    Common names: Bronze Cory
    Distribution: Trinidad, Venezuela, La Plata
    Length: 2.8”
    Water Temperature: 19-26oC
    Description: This is amongst the most frequently, and there is the most common
    of the Corydoras found in aquatic stores. The body shape is arched, with the
    forehead rising quite steeply from a down-turned mouth, around which are three
    pairs of barbels. The flanks are bronze coloured with a darker area immediately
    behind the gill cover which tapers to a point level with the rear end of the dorsal
    fin. These fish are actually sub-tropical fish; unlike many of the other members of
    its family it prefers lower temperatures.

    Figure 4.1 – C. Aeneus


    · Black
    · Red/Orange Laser
    · Green Laser
    · Gold Stripe
    · Gold
    · Green
    · Albino
    · Long Fin

    Corydoras Sterbai
    Common names: Sterbai’s Cory
    Distribution: Brazil
    Length: 2.6”
    Water Temperature: 24.0-28.0oC
    Description: It is hard to misidentify this species but it can be confused with
    Corydoras Haraldschultzi, although the latter is a long nosed species where C.
    Sterbai is the dome headed form - the easiest way to tell them apart is that the
    Sterbai’s Cory has white spots on its head from eyes down to snout. C.
    Haraldschultzi does not. Corydoras Sterbai has recently become available in
    albino form.

    Figure 4.2 – C. Sterbai


    · Albino

    Corydoras Paleatus
    Common names: Peppered Cory
    Distribution: Guyana
    Length: 2.4”
    Water Temperature: 19-26oC
    Description: Adults are easily identified but young can be confused with some
    other Corydoras (such as C. Barbatus and the like) or even young Aspidoras.
    Wild caught individuals look quite different from farm raised fish commonly
    encountered for sale. Wild fish have a higher contrast pattern, the pigmentation
    shimmers like foil in natural sunlight.
    Females grow considerably larger and possess a heavier girth when sexually
    mature (See Figure 4.4). Egg-ripe females can get so robust that the fish cannot
    lie flat against the substrate! The size difference in sexes is illustrated clearly in
    the images below. These fish are actually sub-tropical fish; unlike many of the
    other members of its family it prefers lower temperatures.

    Figure 4.3 – C. Paleatus - Male

    Figure 4.4 – C. Paleatus - Female


    · Albino
    · Long Fin

    Corydoras Trilineatus
    Common names: Three Line Cory
    Distribution: Peruvian Amazon: Rio Ampiyacu, Rio Ucayali and the Yarina
    Cocha. Ecuador: Rio Pastaza.
    Length: 2.8”
    Water Temperature: 16-25oC
    Description: Probably the most misidentified fish commonly found in aquatic
    retailers who incorrectly sell it as C. Julii. The true C. Julii is such a rare import
    that sheer numbers means you are unlikely to really encounter this Brazilian fish.

    C. Julii is similar to the more spotted forms of C. Trilineatus but has no trace of
    any reticulated colour patterning at all and is entirely covered with small, distinct
    spots. Its mid-lateral black stripe is fainter and does not reach as far towards the
    fishes head as in C. Trilineatus
    Figure 4.5 – C. Trilineatus - Male


    · Spotted – Similar to the C. Julii

    Albino: Not a single Species

    Figure 4.6 – C. Sterbai - Albino

    Figure 4.7 – C. Aeneus - Albino

    Figure 4.8 – C. Paleatus - Albino



    "Males are smaller and slimmer. Females grow larger and are much wider which
    can most easily be observed from above." - www.Planetcatfish.com

    Figure 5.0 - Sexing Corydoras

    As you can see from the illustration above females, are larger than the males,
    they also tend to be taller as well. As stated by Planetcatfish.com a good way to
    sex Corys is front above, females tend to be rounder and plumper behind the
    pectoral fins (See Figure 5.0), this is exaggerated when the fish is full of eggs.
    If your fish are young, the sexual differences are not as apparent, another way is
    to look at their Ventral fins. Males ten to have longer pointed Ventral fins, where
    as females have rounder fins, this is an adaptation as the females clasp 1-4 eggs
    at time during spawning between these fins, while looking for a place to put them.


    When you have your tank setup any running and your Corys have settled in, you
    can start to prep them for spawning.
    Depending on what you have been feeding them, you will want to start feeding
    more live or frozen bloodworms, or other such foods, less of the dried foods, and
    more of meaty food.
    Change between 25-50% of the water in the tank with cold water, this will drop
    the tank temp down by several degrees. This simulates the raining season, in
    which the Corys spawn in the wild. I also drop the thermostat down to about 2324*
    C (74-76*F) creating an over all cooler tank setup.
    You should notice that over the next week the female will plump up and become
    apparently fat.
    The males will start to chase the females. You will notice the females start
    cleaning the tank walls; this is in preparation for the eggs.

    From Egg to Fry

    In this section will we look at the collection, and care for the eggs, and also the
    feeding, caring and ‘growing out’ of the fry.


    Figure 6.1.1 – A Cory egg on a leaf

    Once your Corys have laid their eggs, you will want to either remove
    the eggs or the parents.
    It is seen as a better option to remove the eggs from the parent’s
    tank, where the eggs can be hatched under 'clean' conditions.
    Depending on what method you choose, you may remove the eggs to
    separate tank.
    I use a 3 gallon tank to hatch the eggs in; the water is set to around
    26oC. The warmer temperature helps quicker developments of the

    To remove the eggs there are two ways which are widely used, these
    are known as "The Roll Method" and "The Razor blade method"

    The Roll Method

    Apply a slight pressure to the egg, be careful as they will burst. and
    push the egg up the glass, it should come away from the glass and
    be stuck to your finger.
    Now push the egg gently, again, against the glass in the hatching
    tank, and roll you finger down, the eggs should still be sticky and it
    should stick to the glass.

    The Razor Blade Method

    Use a razor blade to scrape the eggs from the glass of the spawning
    tank and then place the eggs on the glass as stated above in "The
    Roll Method"

    The Tank

    The eggs are very susceptible to fungus infections so to help prevent
    these, you will need to add some Methylene blue to the water, be
    careful as this will stain EVERYTHING.
    You will also need to add an air stone, this ensure the water in the
    tank is continuously moving. This will help the fry when they hatch to
    reach the surface to fill their swim-bladders with air.


    The Tank Setup

    There are many techniques used for fry tanks, but the one we will focus on here
    is the bare bottom method.

    Bare bottom Method

    You will need a small tank of between 2-5 gallons, depending on the number of
    fry. The Tank will be completely empty, apart from a sponge filter and the heater.
    Keep the water temp quiet high, around 26oC. In high temps, the fry will eat more
    and grow quicker.
    You will want run a small air-stone for the first few days of the fry’s lives; this will
    keep the water oxygenated, the water moving and also helps the fry to reach the
    surface for air.
    On about day 3-4 you want to install your sponge filter, Huey Hung produces a
    small sponge filter which is excellent for fry tanks, and they run nearly silent,
    depending on your air pump.
    Every day, change between 20-50% of the water, as clean water is essential for
    the first few months. You can make up a bucket of water and use that so the
    water will be room temperature, as sudden drops or rises in temperature will
    cause the fry to die. Make sure you clean the sides and floor of the tank as well,
    as the fry are very susceptible to bacterial infections and fungus.
    The feeding of your fish should be done between 2-4 times a day, depending on
    what you are able to do, if you are feeding microworms you can add a large
    amount each time and get away with only two feeds a day, as the worms will live
    for about 48hours under water.
    Over the next few months the fry will grow rapidly and will need to be moved to a
    bigger tank, after about 3 months the growth rate will slow.

    After about 3-4months the fry should be about 1”-1.5” in total length and will be
    ready to move into your community or Cory tank. They are also now large
    enough for aquatic shops to buy and sell on. You maybe able to get store credit
    or cash for the fish, but don’t just turn up with the fish and demand they take
    Your best method would to be contact the retailer first, and find out if they are
    willing to take the fish off your hands.


    Microworms – By Carmen Webb

    You want to make this as soon as the eggs are laid as t will take a few days for
    the culture to become ready; I make a new culture every 4 -5 days. You can feed
    them to all your fish; they all go absolutely mad for them, especially the Corys.
    Although some large fish will ignore the worms, they will be eaten by small tetra
    and other small fish.

    Required Items:

    Two containers
    Large margarine tubs will work fine, or the tubs you buy for holding
    food stuffs, which are easily bought from a supermarket.

    Ready Brek or some form of prepared breakfast oats, not Scottish oats.

    Dried Yeast

    Micro worm Culture
    Available from some aquatic retailers, or from the internet.

    Pour a splash of room temp water in a cup and add 1 teaspoon yeast. I
    normally leave mine to dissolve properly, about 5 minutes.
    Figure 6.2.1 – Yeast & Water

    Then add 5-6 tablespoons of the ready brek and stir. You'll need to add
    some more room temp water till the mixture is thick, but not roll into balls,
    just slides off the spoon.

    Figure 6.2.2 – The mixture

    Spread evenly on the bottom of your tub, try avoiding the sides. Add the
    microworms and mix them in gently. If you need to add a bit more water to
    make it easier, then do so. But don't add too much, you don't want it
    Figure 6.2.3 – Mixture in Tub

    Once that's all done, place the lid on the tub and store it where ever you
    plan on keeping them. Make sure you have punched holes in the lid
    before hand. I just use the scissors; you don't want them to be gaping
    holes, just big enough to allow air in the tub.
    Figure 6.2.4 – Add the Starter Culture to the mix

    After a couple of days, you should see them climbing up the sides of the
    tub. I use a wooden skewer to wipe them off and feed to my fry. Don't get
    any oat mix on the stick, just worms.
    Pre-Made Foods

    There are a few pre-made foods for fry on the market currently, from crushed
    flakes for livebearers and liquid food for egg layers.
    As we are talking about Corys we will need the Liquid food for egg layers.

    Interpet make a product called Liqui-Fry No1, which is designed specifically for
    egg layers.
    This comes with instructions, although most breeders don’t use pre-made foods
    as they don’t provide the full nutrition that fry need. Most Breeders will suggest
    you use Microworms, which how to create a culture of these has been shown
    above, or vinegar eels.

  2. Chele&Luke

    Chele&Luke Confused Mostly...

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    Awesome article - thanks for sharing :)
  3. gupman

    gupman AC Members

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    No prob..I thought it was a good article..It has pics of each specie but this was the only way i could put it on here is text because i don't have word..
  4. htinkle

    htinkle AC Members

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    Do you have the original link? I'd like to read this in it's original form thanks. Very good article. Did I miss the link to original? Acknowledging the source is important, IMO.
  5. gupman

    gupman AC Members

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  6. ara35

    ara35 AC Members

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    thats great... are there anymore articles on different fish by the same author. i couldnt find any
  7. Studz

    Studz Registered Member

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    CODEKEYGUY Registered Member

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    It said your pdf file is "corrupted and cannot be repaired". However, the Yahoo link shown above works if you use "show as Html"
    Dennis Skea
  9. thomas112393

    thomas112393 AC Members

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    so im guessing no pictus catfish with corys?

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