FAQs on Corydoras Cats
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FAQs on: Corydoras
Catfish Identification, Corydoras
Catfish Behavior, Corydoras Catfish
Compatibility, Corydoras Catfish
Stocking/Selection, Corydoras Catfish
Systems, Corydoras Catfish
Feeding, Corydoras Catfish Health,
Corydoras Catfish Reproduction,
FAQs on: Panda
Corydoras, Pygmy Corydoras spp.,
FAQs on: Callichthyids
1, Callichthyids 2,
FAQs on: Callichthyid
Reproduction, Catfish: Identification, Behavior, Compatibility, Selection, Systems, Feeding, Disease, Reproduction,
Extremely lethargic Cory, high
I wrote about a week ago on another issue, and never received a
<?! We respond to all>
I'm hoping I didn't do anything wrong and my message was just
<More likely some "computer glitch"... As the WWM
"doorkeeper" ala LeGuin's Earthsea double trilogy, I see,
As it is, that issue seems to have resolved itself for the most part.
Now I'm dealing with something in my other tank, and I'm hoping
for some insight from more experienced hobbyists than myself.
Tank: 14gal (functionally about 11-12gal with substrate and lowered
water level), Aqueon filter that came with the "starter kit",
temp steady at 75*F, fully cycled and has been set up since early
December 2010. The pH runs pretty steady at around 8.
<For what species of Corydoras? This is too high... I'd mix in
some water of lower pH... likely RO>
I always treat new water with Prime.
<Likely not necessary, but...>
Residents: 3 peppered Cory cats, 4 albino Cory cats, 2 juvenile mystery
snails. The Corys are being quarantined here, their eventual home is a
55gal. I've had them for about 2 weeks.
Tank stats last night, with API test kit:
NitrAtes: over 80 (YIKES!!!)
<Needs to be addressed... Have you read here: http://wetwebmedia.com/FWSubWebIndex/fwnitrates.htm
and the linked files above?>
I performed my usual 30% water change, all I had time for, with plans
to do another this morning.
This morning, I tested again:
Nitrates: over 40, close to 80 on test kit
Performed nearly 70% water change. Retested.
NitrAtes: less than 40, but close
<You need to do something in addition to simple dilution for NO3
Now for the main problem: One of the albino Cory cats has been acting
lethargic for the last couple of days, is not eating well, and after
last night's water change floated belly-up for a few minutes
despite all my attempts to match temperature, etc. with the new water.
I was afraid we would lose him, but this morning he's better. Not
great, since he's still spending most of his time resting on the
bottom or swimming *very* slowly a few inches, but he's not
floating. Everyone else in the tank, including a new baby balloon molly
that hitchhiked home with the Corys, is acting and looking fine. Even
the snails, which I thought would be the first indicators of poor water
<Much more likely due to the vagaries of the water changes>
The only thing that changed recently is my husband taking over morning
feedings for both tanks for the last week. I think he's been
overfeeding this one, because I don't know what else would have
caused such a large nitrAte spike in such a short time. There was a lot
of "gunk" when I cleaned the tank, which isn't normal.
I've taken over feeding again.
Most of the reading I've done (Google is my friend, yes?) suggests
that nitrAtes aren't *that* toxic over the short term, but these
levels are pretty high and I've seen people mention again and again
that Cory cats are "sensitive" fish. Could the nitrAtes spike
alone be the cause of this little guy's problem?
If so, will continued water changes and much reduced feeding be enough
to resolve it? If not, what else would cause an otherwise
healthy-seeming fish to be lethargic and go off its food with no other
sign of disease? I'm a loss on this one!
<Please read the above citations>
Thank you so much, I appreciate your willingness to help out newbies
like myself with your amazing wealth of experience!
P.S. Is it just me, or are Cory cats just the funniest/cutest little
<Are indeed comical, and faves. I keep them as well>
I was rolling with laughter after their first "feeding
frenzy" over a shrimp pellet!! I'd buy a whole swarm of these
guys if I could, but hubby says no room for more aquariums...
<Mmm, maybe... Bob Fenner>
Re: Extremely lethargic Cory, high nitrates
Thank you so much for the reply!
These are albino and peppered Corys (Corydoras aeneus and Corydoras
paleatus). The lethargic one is an albino.
<The C. paleatus need much lower pH... the Albinos may be either C.
aeneus or paleatus>
I'm in the middle of Kansas, so our water tends to run hard with a
higher pH. Even the "expert" at the local store where I
purchased these guys admitted it's hard to keep soft/acidic setups
here without a LOT of work, <Not so much... easy to mix some tap w/
some RO... Read here:
and the linked files above>
so I stuck with platies for our main fish. I was told that with careful
acclimation the Corys would be ok, and honestly the other 6 look
perfectly fine. I'll look into the RO water option, but if I
can't get the pH down enough, should I find a new home for these
I'm not sure what I'd replace them with. (My 7yo son wanted a
school of glass catfish, but there's no way we'd be able to
keep them healthy. The Corys were a compromise, since most other
catfish types he liked get too big.)
<There are many tools that can/will help you identify fishes, other
aquatic life that enjoys your quality water>
I use the Prime instead of whatever brand dechlorinator came with my
starter kit because we have copper piping in my house. I wanted to be
extra careful to avoid getting copper in my aquariums and killing
The albino Cory is still alive, but he's pretty much the same as
yesterday -- not swimming much, resting on a rock most of the time. I
haven't seen him eat. I did one more water change last night, being
careful to get the rest of the "gunk" out of the gravel. The
nitrates are now reading between 10-20ppm, which is where the tank was
before its regular water change the previous week. I'm going to be
feeding lightly and testing the nitrates daily for the week, I think.
I'll also be buying some more plants soon, so that will probably
help a bit.
I read as much as I could about Corys/nitrates/etc. on WWM and the
'net in general before I posted, but I probably missed something.
I'll go back and check out the links again. Thank you again for the
<Certainly welcome. BobF>
Cory playing dead 11/5/10
Thanks for all the great work you do. I'm hoping you can help me
One of my four albino Corys has been behaving very oddly over the past
He eats normally with the others each morning and swims around a bit
but then spends much of the rest of the day lying on his back,
appearing to be dead, until he is poked or touched by something. The
first time I saw this I thought he was dead but when I went to net him
out of the tank he immediately jumped up and started swimming around
Each day since then I have noticed him doing the same thing but as soon
as I put the net near him he rights himself and swims away. I saw him
do the same thing when he was nudged slightly by another fish.
Is he really sick or is there some other explanation for this weird
behaviour? The other three are behaving perfectly normally.
Thanks very much
<Mmm, well, Corydoras can be/act like real clowns at times, but
laying on their back or sides is not normal, healthy behavior. I'd
look about for an anomaly water quality wise, or at least act
proactively and institute a series of daily partial water changes and
gravel vacuuming. Bob Fenner>
Itching Cory Catfish 7/10/10
You've been helpful in the past when I had questions about my first
aquarium and some stocking advice for my second, so thank you.
I did want to ask something about 6 new Panda Cory Catfish I added a
couple weeks ago.
<A low to middling temperature fish; don't keep warmer than 25
They are the newest inhabitants to a ~4 month old cycled aquarium. They
share a 46 gallon with a school of 9 Harlequin Rasboras, 6 Cherry
Barbs, 3 Oto Catfish, and one last cycling Platy that's been tough
to net out.
<OK. These should all do well at 24-25 C/75-77 F. Any warmer will
stress the Platy, Otocinclus and Corydoras.>
Anyhow, as of yesterday morning I noticed one of the smaller Cory
catfish do a few quick darning motions in the gravel on his side while
scavenging for food. He only did it a couple times until the others
joined him to start eating the pellets I dropped for them. I looked at
the fish but didn't appear to have anything on his side, nor any
discoloration (nothing I can see), and he's been actively swimming
and searching for food as always. Then this afternoon, about an hour
after they finished eating any dropped pellets, I saw the same behavior
again; 2-3 quick darts in the gravel, and only in the gravel not on the
decorations where I normally feed the catfish. It is a normal aquarium
gravel, black, not sand nor a fine gravel that I've heard Cory
catfish like to dig into.
<Hmm... "like" is perhaps not the right word to use here.
Corydoras kept in tanks with gravel, especially sharp gravel, suffer
from abrasions, in particular to their whiskers. You can instantly spot
Corydoras kept in tanks with gravel because they have almost no
whiskers, whereas those on Corydoras kept in tanks with smooth silica
sand have whiskers that are very long, half an inch maybe. It's
quite striking. While the missing whiskers aren't fatal, they do
indicate that the fish are being damaged and vulnerable to secondary
infections, which is a warning sign that all is not well.>
I still cant see anything wrong with him nor any of the other fish,
including any of the other catfish. He still swims actively around and
all over the decorations/plants as usual looking for food, so he
doesn't appear sick.
<Flashing can be a variety of things, but the most common are
ammonia/nitrite above zero; Velvet; and Ick, in that order. Just
because you can't see any other Velvet or Ick on the fish
doesn't mean there isn't any in the system. Both these
parasites go for the gills first.>
I guess I'm just curious if this is some kind of feeding behavior,
like trying to scare up any buried food particles,
<No, Corydoras don't do this. When feeding on sand they plough
their heads straight down, and spew the sand through their gills.
It's fun to watch, and no-one who has kept Corydoras with sand EVER
goes back the gravel. I'm not saying you can't keep them with
gravel, but it's far, FAR inferior in terms of fun, both for you
and the fish.>
or something of the sort and nothing to worry about, or if it's
some sign of a disease that just isn't visible?
Water conditions for the past few weeks before adding the Cory catfish,
nitrite 0 ppm
nitrate ~5ppm (weekly water changes)
temp ~79F (extremely tough to keep any cooler in summer in Florida
w/out a chiller)
<Will cause problems if it stays this warm. Do increase evaporation
and try floating litre-sized blocks of ice in the aquarium.>
hardness ~200KH ~150GH normal for this area (but no problems with
Platies and Cory catfish in a different tank for over 1 year)
<Indeed, water chemistry isn't a major problem for Corydoras,
and Platies obviously prefer medium to very hard water.>
Corydoras ID -11/18/07 Lord, I hate to bother you all
again. But I've spent several days at planetcatfish.com
trying to ID this little Corydoras catfish and can't seem to
find what he/she is. I ordered Corydoras trilineatus and 2 of
these came in the same batch. I'm putting them all in the 125
gal with the Severum (after 4 wks quarantine). I'd like to
get a few more of this species because I noticed Corys seem to
hang out with their own species pretty often and I want them to
be comfortable. If you can ID him for me I'd certainly be
grateful and so would the little Cory. Thank you all, you're
the most wonderful group of volunteers I've ever encountered.
Mitzi <Hello Mitzi. Your catfish could well be Corydoras
trilineatus. As you perhaps realise, Corydoras trilineatus and
Corydoras julii are routinely mixed up. In fact many catfish
experts reckon that most of the fish sold as Corydoras julii are
actually Corydoras trilineatus. The give-away is the head:
Corydoras trilineatus has black worm-like markings on its head,
whereas Corydoras julii has discrete, approximately circular
spots. Because your fish doesn't seem to have those spots on
its head, I don't think it is Corydoras julii. I agree with
you that Corydoras are happiest in big groups. Six specimens
seems to be the minimum to really get the most from them. Kept
like that, they are less shy and more entertaining, as well as
easier to breed. Thanks for the kind words, and hope this helps.
Corydoras ID/tank height -11/18/07 I have a PS to the
email below I just sent. I just read a quote from Neale at
"<Circulation of the water is important. But also how
deep is the tank? Corydoras are obligate air breathers, and they
will literally drown in an aquarium too deep for them. For the
smaller species, around 30 cm is about right. Anything over 45 cm
is dodgy, in my opinion.>"
Platy - Gourami mix revisited: this time,
+cats! 2/2/06 Hi crew!
Thanks for your quick+informative reply regarding my
platies! The little guys look very happy! I followed your advice
and bought a test kit: all very good readings:
Ammonia: 0 Nitrate:0
Nitrite:25 - 50 <These last two are
crossed-over... and nitrate's a bit high. Do try to keep
below 20 ppm... means covered on WWM> Ph: not
sure, as it was a funny light blue colour, but I'm guessing
it was about 7.5, and they told me not to worry about it at my
local fish store place. <Is likely fine...
also covered> I did not buy the gouramis, as
planned, but instead bought 2 little cats. I hope to get the
gouramis later. My question is
about my cats. In the shop, they were labeled as "speckled
cats", but when I got them home and looked in a fish book,
there was a picture of them... Labeled as peppered Corys! I
can't send a pic. with this, but I'm working on it! They
seem very peaceful and fun loving, could they be the peppered
Corys? <Are very likely a species of
Corydoras... maybe paleatus... covered on WWM... fine here>
Thanks for replying to my email, and once again,
thanks for your great site! <Welcome. Bob Fenner>
This had occurred to me before but now I'm extremely
concerned. The 125 gal tank I planned to put 12 Corydoras into is
22" tall (or 60 cm). Is that going to be too tall for them??
If it is I'll just buy them a 40 gal long and put some
Hatchet fish in with them. Just when I think I'm done
worrying I find out I'm not :-( I'd love to hear your
opinions. Mitzi <Hello Mitzi. In deep tanks, small Corydoras
may struggle to reach the surface. In a plain aquarium, 45 cm may
be taken as a safe depth of water for medium- to large-sized
species like Corydoras panda and Corydoras aeneus. Smaller
species, like Corydoras hastatus, shouldn't really be kept at
more than 30 cm depth. In deeper tanks, it's generally
recommended you go with Brochis rather than Corydoras spp;
Brochis are altogether stronger swimmers and naturally come from
relatively deep waters. Corydoras are very much shallow water
fish that inhabit creeks and streams rather than rivers. My
peppered Corydoras live in a tank where the water is about 40 cm
deep, and they seem fine. What I have noticed is they often rest
half-way on stiff plants such as Anubias. So, if your tank is
unusually deep, you might incorporate such resting places so that
their life isn't too difficult. Do note that I'm talking
about the depth of water rather than the depth of the tank; by
the time you allow for the depth of substrate and the air space
at the top of the tank, your 60 cm aquarium will likely only
contain around 50 cm of water depth. While still deeper than the
optimum, with a few robust plants, bogwood roots, or rocky
ledges, your catfish should be fine. Cheers, Neale.>