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FAQs on  Corydoras Cats: Behavior

Related Articles: Callichthyid CatfishesSummer loving: cats in the garden, kittens in the kitchen by Neale Monks,

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FAQs on: Callichthyid Identification, Callichthyid Behavior, Callichthyid Compatibility, Callichthyid Selection, Callichthyid Systems, Callichthyid Feeding, Callichthyid Disease, Callichthyid Reproduction, Catfish: Identification, Behavior, Compatibility, Selection, Systems, Feeding, Disease, Reproduction



Corydoras bilineatus 'San Juan'; obs. to share.       5/28/16
Hello guys,
<Hello Joanne,>
I recently got a group of 6 Corydoras bilineatus 'San Juan' and thought I'd share a few observations.
<Please do.>
These were recent imports but they all look healthy and are settling in well. They eat anything that comes their way and don't seem to be very fussy in regards to temperature or water hardness/softness.
<True for the genus Corydoras generally, provided extremes are avoided.>
What little information I could find about them suggests that they are somewhat more delicate than the majority of Corys and are sensitive to water parameters (at least as regards to breeding).
<I think that's probably true for most of the wild-caught Corydoras. Hardy, but not quite so hardy as the farmed fish that most aquarists are familiar with.>
Most information I found suggests that these are not easy to breed. I wonder if this is due to any innate sensitivity or if it is just that these Corys have not been bred in captivity for lots of generations.
<Oh, yes, I do agree with this; long-term farmed fish generally spawn without the same need for triggers that wild-caught fish require. Those fish one or two generations down from the wild fish probably require these triggers too.>
Look at angels and discus, the wild caught fish are much more sensitive and more difficult to acclimate or breed than the strains that have been in captivity for a long time.
<Precisely. Farmed Discus are immeasurably easier to keep than the wild fish.>
The other thing I have seen is that these fish are definitely mid-water swimmers. That was a surprise!
<Indeed! But in fairness, Corydoras bilineatus is one of the "Corydoras elegans" group that are more midwater-y than some of the other tribes of Corydoras. There's a whole range really. From almost tetra-like midwater swimmers at the Corydoras habrosus end of things right the way through to the long-nose Corydoras such as Corydoras septentrionalis that spend a huge amount of time snout-deep in the sand. The body shape is a good clue, the robust, deep bellied shape of Corydoras elegans-group catfish contrasting with the long-snouted, flat bellied shape of Corydoras septentrionalis.>
There are other mid-water Corys of course but they are definitely a minority. When I feed the tank they will go down to the bottom to get food, but the rest of the time they like to swim in the middle of the tank.
They like to "vacuum" the plants and will even swim near the surface to nibble on the roots of the floating plants.
<This sounds all very normal to me. Corydoras generally will do precisely the sorts of things you describe given the opportunity.>
I haven't found any written references to this behavior but did find some videos on YouTube where they behave exactly the same way. Other than this they have typical Cory behavior.
If you know of any special requirements for these Corys I'd love to know!
<Corydoras bilineatus isn't widely kept, but anything said about Corydoras elegans applies to them. Overhead shade, coolish water (22-24 C is ideal), lots of oxygen, and not too much depth (they need to be able to gulp air from the surface easily) are the main things. Avoiding very hard water is helpful, but Corydoras generally seem much less fussed by water chemistry than water quality and oxygenation. Obviously the bigger the group, the better. Sandy substrate is, in my opinion, a must.>
<Thanks for your very informative observations. Will certainly share!
Cheers, Neale.>
Re: Corydoras bilineatus 'San Juan'      5/28/16

Thank you! I had not realized these were in the C. elegans group, that is very helpful.
<Ah yes; there are various reviews of the genus, some accessible via Google Scholar.>
They are in QT right now, was planning on putting them in my community tank but now think it would be nice to set up a tank just for them. Sand bottom, lots of plants. It would be nice if I can get them to breed!
<Presumably much like C. elegans, though that certainly isn't as easy to breed as some of the others; I've bred Corydoras paleatus of course, but then again, who hasn't?!
As suggested in the above article, a diverse diet and the use of cool water are probably important spawning triggers you could try.>
Thanks again!
<Most welcome. Neale.>

Cory keeps burying head in the sand      1/25/16
Hi crew, I have had a small school of albino Corydoras for about 7 months now. Thanks to your help they have all been healthy and happy since I got them. For about a week now, one of my cories has spent most of his time with his head buried in the sand(In case it's relevant- not positive he is male but pretty sure). The first day I noticed he had his head buried
just below his eyes. I had to swish a net around him to make sure he was alive. Since then I've seen him with his whole face buried in the sand, eyes buried as well, for sometimes 5 hours or more each day. He seems to keep choosing the same spot- a rock with a good amount of algae around the base of it. When his eyes are visible it's clear that his gills are pulsating and he's definitely alive. Possibly unrelated but I've also noticed another albino Cory has some reddish areas are the base of his tail. All of my parameters seem to be normal (ammonia 0, nitrite 0, nitrate 20, ph 6.8, kH 5, gH 6). Not sure what I am missing here. Thank you
sincerely for your help. Danielle
<It's normal for Corydoras to stick their heads into the sand while feeding. They will even pump sand through their buccal cavity and spew it out their gills, extracting any edible morsels they find! So in and of itself, this isn't a symptom of anything wrong. However, red sores on the base of the tail, together with lethargy, can be signs conditions in the bottom of the tank are not ideal. Check the sand is soft (not "sharp") and lime-free; stir the sand periodically to keep it clean (or use burrowing
snails such as Clea helena to do this for you); and if the red gets worse, treat as per Finrot. Cheers, Neale.>


albino Cory barbell loss, going for air                  ‏            11/9/14
Hi there,
My name is Gabby and I'm new to aquariums (had one since August) and loving it.i've slowly built a community tank (doing lots of research) since then and it's gone quite well.
I have a question about my albino Cory. I have a group of four and yesterday saw that the smallest one had lost his barbels. Today, I've seen him go up for air quite a bit, much more than the others. He's still quite
active, but during feeding seems to have eaten less than the others. Should I just keep monitoring him? Any suggestions?
<Catfish lose their barbels for two reasons. Or rather, there are two things going on that interact, resulting in the barbels getting shorter.
Keeping Corydoras catfish in tanks with gravel (especially sharp gravel) rather than sand causes the barbels to get damaged. Very fine (sometimes called "pea") gravel is better than regular aquarium gravel, but the best
substrate is silica sand (a lime-free sand, sometimes called "pool filter" or "smooth silver" sand). What happens is the barbels get damaged, and that's when the second part of the process, bacterial infection, sets in.
The bacteria cause the tissue of the barbel to die back, and over time the barbels get shorter and shorter. Improving filtration and water flow along the bottom level of the tank can help. Some filters (especially small
internal canisters and hang-on-the-back designs) often don't "suck" much water from the bottom and the outflow is very much directed along the top of the tank. This means the lower half of the tank suffers from low oxygen
levels, which causes catfish and loaches to swim up and gulp air. Note that under optimal conditions Corydoras rarely gulp air -- they're very much "facultative air-breathers" meaning they only breathe air when forced to do
so. That's unlike Bettas which are "obligate air-breathers" meaning they will suffocate if they can't breathe air because their gills are proportionally smaller than they should be (in the wild, Bettas live in places where the water doesn't hold much oxygen, so relying on their gills alone would be pointless). Anyway, under better conditions the barbels grow back very quickly, and on healthy Corydoras you'd be surprised how long they get, not far off half an inch!>
I also have a question about his lost barbells. When I decided on Corys, I decided on sand. The guy at the aquarium shop told me coral sand works, but now I'm wondering if it's the cause of his barbell loss.
<Coral Sand was a terrible choice. Bad advice from the retailer there!
Coral Sand is made of limestone. It's from the sea, basically mashed up seashells and corals. It makes the water hard and alkaline (i.e., raises the amount of minerals in the water as well as raising the pH). Over time, this stresses most freshwater fish. (Not all: livebearers and Rift Valley cichlids LOVE coral sand because it creates conditions they want. But Amazonian and Southeast Asian fish come from soft, acidic habitats and they aren't going to do well in tanks with lime-rich sands.>
The other three and their barbels are fine. Is this sand too rough?
<See above.>
Any thoughts or recommendations would be much appreciated. This little school is rivaling my Betta for favourite status, and I want to make sure they are healthy and happy.
<For sure a fun group of fish, the genus Corydoras.>
Thanks in advance,
<Most welcome, Neale.>
Re: albino Cory barbel loss, going for air                  ‏            11/9/14

Hi Neale,
Thank you for your quick response! I'll go out and look for silica sand right away.
<Cool. Aquarium shops sell it, but it's often cheaper at garden centres.
Just clean it well, or you'll make the tank really cloudy.>
What would you suggest to increase oxygen flow at the bottom of the tank? I have a hang off filter.
<If all else fails, an airstone weighted down so it draws water up from the bottom of the tank (that's what the air bubbles do) to the top of the tank.
Cheap and cheerful. Alternatively, there are all sorts of small pumps called powerheads that do the same thing electrically. Finally, you could buy a small internal canister filter and place it somewhere at the bottom of the tank, maybe hidden behind some rocks or plants, and let it push the water around.>
Man, so much to learn still!
<Part of the fun of the hobby is the learning. Corydoras are easy fish, and very reliable for beginners, but there are one two issues with them. Would direct you to this page:
Various links at the top that will take you to interesting/relevant articles. Cheers, Neale.>


Cory Cats; sys., beh.     11/2/14
Hello, hope all is going well there. I have a question about cories, please. I have 6 sterbai cories in a 38 gallon innovative marine aquarium which is 19 inches high. In the past in other tanks I have had cories swim to the top on occasion for gulps of air and then go back down to the substrate. But now it seems these cories seem to swim up and down a lot and across the tank a lot and I have never seen one go all the way to the surface. Is this because the tank is so high? The water quality is good and the cories seem to be healthy. Thanks,
<Yes, James, Corydoras can have trouble swimming all the way to the top.
Like most catfish, they lack big enough swim bladders for neutral buoyancy, and need to active paddle upwards or they sink. In the wild they mostly live in streams that barely cover their backs rather than the main rivers.
So water depths in the 20-30 cm/8-12 inch range are ideal for Corydoras, with up to 45 cm/18 inches generally acceptable provided (a) the water current isn't so strong that the catfish have trouble swimming upwards and (b) there aren't any boisterous or aggressive tankmates that might harass them as they swim to the top. Water temperature and water circulation are critical factors too. Corydoras are facultative air-breathers, meaning they only breathe air when they need to. Cool water has more oxygen than warm water, which is one reason Corydoras mostly do best between 22-25 C/72-77 F, and only one or two traded species, notably Corydoras sterbai, being truly happy up to 28 C/82 F. In cool water they may hardly ever gulp air.
Water circulation at the bottom of the tank is what ensures there's oxygen down there for them to use, but most filters operate by pushing water along the top of the tank. Water circulation at the bottom of aquaria can be pretty poor, so review your system, and act accordingly. Adding an airstone or a small powerhead could make all the difference. Again, if the bottom layer of water is well oxygenated, they may not need to gulp air. If your Corydoras seem otherwise happy, chances are they're fine, but you're right to be open minded. Although Corydoras are normally very hardy, some mysterious deaths of Corydoras could easily be down to suffocation in situations where they need to breathe air but for some reason aren't able to do so. Cheers, Neale.>
Re: Cory Cats    11/2/14

Thank you Neale
<Most welcome.>

Albino Corydoras bubble nesting?    1/14/13
Hi there. I have two albino Cory cats in a 10 gallon tank with my Betta boy. The larger of the Corydoras has always been a very busy, robust fish.
For the last month or so, he
<Mmm, she>
 sometimes sits at the top of the tank, seemingly making a bubble nest.
<Ah, no... Corydoras as substrate spawners... but do facultative (non-obligative) aerial respiration... as many Amazonian fishes are capable of... the bubbles are likely from polar molecules in the water (foods, wastes... lack of complete filtration, insufficient water changes)...
coalescing/keeping exhausted air bubbles encapsulated... from the cats, Betta>
I know there are some catfish that do make bubble nests, and that Corydoras are not among them...
so, any thoughts on the behavior?
<Breathing from the surface, exhaling underwater>
The tank is about a year old, cycled, stable. It has several live plants, and no surface "oil" that would prevent oxygen transfer.
<Ahh! Good point>
I wonder if the fish is actually a different species (though it looks like a Cory to me) or if the little fella thinks he's a Betta... just kidding. I would appreciate your insight.
<As stated. Quite common. Bob Fenner>

Extremely lethargic Cory, high nitrates   2/21/11
<Hello Angela>
I wrote about a week ago on another issue, and never received a reply.
<?! We respond to all>
I'm hoping I didn't do anything wrong and my message was just overlooked!
<More likely some "computer glitch"... As the WWM "doorkeeper" ala LeGuin's Earthsea double trilogy, I see, post all>
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:
Ammonia: 0
NitrItes: 0
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:
Ammonia: 0
NitrItes: 0
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 here>
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 quality.
<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.
<Ah good>
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?
<Mmm, yes>
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!
--Angela S.--
P.S. Is it just me, or are Cory cats just the funniest/cutest little fish ever?
<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    2/21/11

Thank you so much for the reply!
<Welcome Angela>
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 fish?
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 snails/fish.
<Real good>
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.
<Will help>
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 response!
<Certainly welcome. BobF


Cory playing dead 11/5/10
Hi Crew,
Thanks for all the great work you do. I'm hoping you can help me again.
One of my four albino Corys has been behaving very oddly over the past few days.
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 normally.
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
Hello again,
<Hello Brian.>
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 C/75 F.>
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 these:
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?
<Likely so.>
Water conditions for the past few weeks before adding the Cory catfish, and still...
pH ~7.5
ammonia 0ppm
nitrite 0 ppm
nitrate ~5ppm (weekly water changes)
<All fine.>
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.>
Thanks again,
<Cheers, Neale.>

Cory/Oto behavior change  5/19/10
Hi crew:
Thanks as always for all that you do.
<Kind of you to say so.>
My question concerns a change in behavior by some of the fish in my tank. Tank specs as follows:
Tank: 10 gallon standard
Filtration: Aqueon 10 HOB with pre-filter sponge (x2) each rated for 100gph
Temp: 76F
pH: 7.2
NH3: 0ppm
NO2: 0ppm
NO3: ~10ppm
Above tested via API Freshwater Test Kit
Total Alkalinity: 180ppm (tested via strip... not really sure what this number represents)
<Middling hardness, fine for most purposes.>
Total Hardness: 120ppm (tested via strip... not really sure what this number represents)
<Similar. Do read:
20% water change weekly
Flora (moderately planted):
Cryptocoryne wendtii x2
Cryptocoryne parva x2
Anubias barteri v. 'Nana'
Microsorium pteropus
Ceratopteris thalictroides - rooted
Eleocharis acicularis
Remnants of Java moss - mostly removed as it was constantly infested with thread algae
<Yes, never had much luck with this plant myself. Always seems to do well where I don't want it, but badly everywhere else.>
Hitchhiker duckweed
<The world's best ammonia remover! A blessing of sorts, but a nuisance I know.>
Corydoras pygmaeus x6
Boraras maculatus x15
Otocinclus affinis x3
Assassin Snails (started with 2 adults, now numerous juveniles)
Hitchhiker pond snails
<Sounds grand! It's a real joy to read about a sensibly stocked 10 gallon tank.>
Tank was set up and planted in October, stocked in January.
I've observed a change in behavior in my Corys and Otos over the last few weeks. In the past, the Otos would spend time on the front and side glass of the tank during all hours of the day/night. Lately, they stay in the small space between the HOB filter and the back glass of the tank.
<Possibly more food there?>
They will venture down to the substrate at night to eat algae wafers (Hikari brand), but ignore the blanched zucchini and carrots I place in the tank which they used to eat with gusto.
The Corys, while always skittish, used to venture around the tank in a shoal, especially when I fed the Rasboras. After not seeing any of them for weeks, and assuming they had perished somehow, I found them hiding in a tiny crevice, all on top of each other, between the driftwood and the substrate, when I shined a flashlight into the tank to try to find them. They also now seem to venture out only at night for the sinking wafers (Hikari brand) I place in the tank at lights out. I know that Corys are nocturnal in the wild, but this is a recent development, hence my concern.
I'm not sure what caused the change in behavior as my feeding and maintenance regimens have remained the same. Water quality has also remained constant.
<That would be my first though, as well as variation in pH and problems with oxygenation. Since both Otocinclus and Corydoras prefer cooler rather than warmer conditions, check the temperature. 25 C/77 F is the absolute tops for both species.>
My first thought is an aggression issue with the Rasboras, but I have never observed any aggression.
I had also thought that I might need to add Corys to the tank to see if increasing the size of the shoal would bring them out into the open more often, but I believe my tank to be fully stocked as is.
<Oh, I'd chance it. With all the plants I think you'd be fine. I'd keep at least 5 Otocinclus, and maybe double the number of Corydoras pygmaeus. All these fish are so small that their impact on water quality would be fairly trivial.>
Do you have any thoughts on what would cause this change in behavior and if there is something else I should be doing?
<My guess would be something is scaring them -- too much overhead light, noise/vibration outside the aquarium, banging doors or some such. Direct sunlight can also be a thing. I have a 15 gallon tank that gets direct sunlight for a couple of months of the year, and the way the fish behave becomes noticeably different during those times. The Corydoras paleatus in particular cluster in one particular shady spot under the Anubias mother plant.>
Thanks in advance.
<Cheers, Neale.>

My Corys... repro. beh.    11/3/07 Hi WWM crew nice work you guys are doing. Hi my Corys are acting strange, I have two albinos and 2 peppered. The peppered seem normal but the two albinos are just weird. One day I looked into their tank and found some eggs tried hatching them they just molded over. a few weeks later I look at my smaller of the two Corys and she's laying eggs. I was like wow because the other albino Cory is twice as big as her and has the characteristics of a female. (Big rounded belly, rounded fins, etc.) every time I take the eggs out they don't hatch every time I leave them in they eat every single egg, what's going on and what should I do? <Breeding Corydoras isn't too difficult. The usual problems are dirty water (which causes the eggs to fungus); snails (which eat the eggs); immature catfish (which don't seem to produce healthy batches of eggs and milt); and the wrong water conditions (lack of the correct spawning triggers). Sexing Corydoras has nothing really to do with size, though fully grown females do tend to be bigger than fully grown males. The shape of the dorsal fin is usually the best clue. Regardless, once they start spawning, you'll know which are the males and which are the females. In any event, I've written a long article on breeding these fish for WWM, so have a read through that and it should answer your questions: http://www.wetwebmedia.com/FWSubWebIndex/coryreproart.htm . Hope that helps, Neale>

Cory cat behavior or disease  - 05/01/07 Dear crew, Tank specs:  10 gallon, heated to 79 degrees (with a heater that won't stay attached to the side of the aquarium, driving me crazy and always having the tip touching the gravel*. is this a problem?), <No> filtered with a hang-on filter rated for 5-15 gallons, ammonia 0, nitrite 0, nitrate 5 30 minutes before weekly maintenance which consists of a 20% water change, quite often twice a week, a swish of the filter in aquarium water or a change if needed, hand picking of algae <Shouldn't have much of this...> and an occasional swish of the sponge media when there's too much algae.  Eco-complete substrate, java moss, a planted plant I can't remember the name of and a floating Anacharis that tends to tip more then it floats.  One small lace rock. <I'd pull this... soak in some warm/boiled water... test the water for phosphate... may be a principal contributor to your algae growth...>   Plant light florescent for the lighting, on about 12 hours a day.  Two panda Cory cats, two albino Cory cats, a male Betta and lots of pond snails (that I purposefully introduced*. I like them).  Feeding twice a day with tropical flakes for the Betta, shrimp pellets for the Corys, frozen white worm larvae, frozen daphnia and Brine Shrimp Direct's Beef heart Plus flakes for all.  (My Cory's LOVE the beef heart flakes.)  Feeding is switched up every day, one thing at a time, so no, I'm not feeding everything all at once.  They fast one day a week as well as fasting my plants one day every two weeks or so (which has done wonders for algae control). <Mmm...>   The tanks been set up for a couple of months with fish just being added in the last month or two.  No quarantine as the place we bought the Corys quarantines and the Betta was added first.  Whew!  I hope that's all the information you need. My problem resides with my Corys.  First, I was told they would school together, which they don't.  The pandas live under the heater and the albinos swim around.  I would like to get more of each to complete the school.   How many Corys could I comfortably fit in the 10 gallon? <Well... I'd rather that you had just five or so of one species...> We have two other larger tanks that I could move either school of Corys in if there's not enough room to complete the schools in the 10 gallon.   <Oh! Good... small, odd numbers of this genus are best in most hobbyist settings... One species if the systems are small...> Second problem.  I used to have a fifth Cory cat, albino.  Two weeks ago he became paler then the other albinos, no pink cast to his body.  He would still scrounge around for food when I fed them.  (I feed them at the same time in the same place every time.  Even the Panda cats know when to come out.)  But other then that, he appeared rather listless.  He would even 'waft' in the current and tip a bit. But when I bumped him or another fish bumped him, he would move a little.  However, I happened to be leaving that day for a five day vacation and worried that he would die while I was gone and rot in my tank, causing havoc to everything else, I froze him.  Now one of my other Cory cats, who used to be active and pinkish, is acting the same way.  He acts more active when he's scared into moving, but other then that, he just sits around, blinking, with not much gill movement (though I know they're labyrinth breathers, <Yes... of a sort... facultative...> so I don't know whether this has much to do with it).  I watched him eat last night, so I know he's still doing that.  This has been going on for 3-4 days now with no further deterioration of his condition.  So now I wonder, is he sick or did I freeze my last Cory cat unnecessarily? <Maybe> There are no other physical signs of illness that I have noticed besides what is described above.   I sincerely hope that I haven't just missed the answer in the FAQ section.  I have read through the catfish behavior and disease three times and Googled different terms related.  I hope I haven't wasted your time.  Thank you again for your help. Celeste <Thank you for your thoughtful, well-worded questions, comments... I would move the non-Panda species here... and keep it/them in a bit cooler water temp. wise... Do please see WWM, Fishbase.org re the water quality of these species in the wild... Is your water particularly hard, alkaline? Lastly, a cursory note re nitrogenous et al. waste accumulation and these (and most Amazonian) fishes... They do appear ataxic (disoriented) as you note, under such influences... better to have larger volumes, well filtered, maintained to avoid such poisoning. Bob Fenner>
Re: Cory cat behavior or disease   5/2/07
Bob, <Celeste> Thank you for your prompt reply.  I must admit in my Wet Web Media addiction I was rather worried when daily FAQ's weren't updated at all this weekend. <Heeee! Glad you noticed> I'm glad to see you alive and well.  I hope that going from Hawaii to Canada wasn't too much of a shock. <A bit sleepy... well, sleepier... but many nice folks about, good things to do... Fab meals and drinkies>   I can only imagine how much (volunteer) time you spend on this website daily. <A few to quite a few hours... are you able, ready, willing to join us... Yet?> I really appreciate the value you, as well as the other volunteers, bring to this hobby. <Thank you my/our friend> The Albino Cory Cat wasn't doing as well this morning.  He was sideways under a plant and didn't come when I fed them.  It wasn't until a few minutes later when I swished the plant a bit that he righted himself and started swimming around.  After receiving your email, I called my husband and had him move the two Albinos into our Tetra tank.  That tank is a degree or two cooler and softer then the water in my tank, has been set up for over 6 months and is 37 gallons. <Good>   I've never tested the 10 gallon tank hardness, honestly.  I use half filtered tap water that has the chlorine, etc. removed but leaves the minerals in and half RO water.  The tap has a hardness of 11 or 12 while the RO has a hardness of between 0-1.  I estimate that it is about 6 or 7.  I will check tonight. <Also good... often there are other sources (gravel, decor...) that can/do add to hardness...> But I know that the Tetra tank is between 4-5 with a Ph below 7.0.  (My husband is in charge of testing the other tanks so I don't know the exact numbers.  I just know that we've reached our target numbers for that tank.)  Next time we're at the good LFS, we'll pick up more of both types of Corys. <Sounds good> In the 37 gallon, we have 2 ADFs, 10 Neon Tetras, 5 Flame Rios Tetras and 6 Red Eye Tetras.  (Now I'm all paranoid and confused about my capitalization after today's daily FAQs.) <Heeee! No worries... missals w/ only a scattering of errors I pick up, mostly through the software...>   Someone at the LFS (not the good one, the one that advised me to put 2-3 goldfish in the 10 gallon with my Betta.... obviously, I didn't) told me that bottom dwellers don't factor into the inch per gallon rule, that's it's more a psychological thing. <Mmm, not so> I could therefore leave the ADFs (and at the time, 3 Loaches) out of the equation when stocking my tank.  But I have not been able to find anything to substantiate that claim. <There is naught>   I can't imagine that I could have 37 inches in the water and 37 inches on the bottom, especially since Cory Cats are probably messier then, say, the ADFs.  How many Cory's could I have in this tank? <Mmm... depending on species, perhaps 15...> I have to admit I fell in love with the school of Panda Cat's at the LFS with about 50 of them.  There's just something about seeing them swim together that makes them that much cuter. <Yes> Last thing, I promise.  I thought we had done our research on lace rock before we bought them but apparently not after Googling it on WWM this morning.  There's some in all three tanks.  We have algae in all of our tanks, though it's not the slimy type (BGA) but the course, thick stringy kind that comes out fairly easy.  The tetra tank is the worst and that's had the lace rock the longest.  My husband pulled the rock out this morning.  Phosphate testing kits are not easily found here and we may have to order one.  We thought the algae was an over-feeding problem and would straighten out once we separated the live bearers into their own tanks (which we did two months ago).  I am slightly confused about your instructions to place them in warm/boiling water.  Will this remove the phosphates in the rock? <Mmm, only to an extent... removing the more easily soluble source near the surface... in time, the deeper, more concentrated layers become exposed...>   We boiled all the rock before placing them in the tank, but would further boiling help with the phosphates if there are any? <Only temporarily> Or should we just leave them out and find something else to decorate?   <Is one approach... Using more (i.e. purposeful photosynthetic growth), utilizing chemical filtrants, limiting other essential nutrients... are others> Thank you again, Celeste <Welcome my friend. Thank you for writing so well, clearly. Bob Fenner>
Re: Cory cat behavior or disease -- 5/4/07
Bob, <Celeste> We unfortunately lost the Cory Cat last night.  Water hardness tested at 8 with Ph at 7.4, which is higher on both accounts then I thought.  (Ah, the importance of frequent testing.)  According to fishbase.org, that's within acceptable range, but I would like to see it lower then that. <Mmm, yes> I did a 20% water change last night using only RO, and will continue to do so until dH is 6 and Ph below 7.0.   <Good> (The Tetra tank where I moved the Albinos is dH - 5, Ph - 6.4.)  We plan on buying 10 more Albino Corys and 3 more Panda Corys this weekend.  (Well, probably just 4 Albinos this weekend and 6 next weekend....keeping them odd and letting the bacteria catch up.) Well, thank you for asking about joining the crew!  I do have the time and I am very willing, however, I've only technically been part of the hobby for 6 months.  (Though I grew up with a freshwater tank in my house, I only did water changes and the like when it was my chore.)  As a self-proclaimed researchaholic, I know quite a bit about the things I've dealt with (plants, DIY CO2, setup, cycling, Ick, Guppies, Tetras, Loaches, Bettas and Cory Cats, those kind of things), but only general things about other aspects of freshwater and next to nothing about marine.  You guys have done enough for me, if I can return the favor in anyway, I would happily do so. Celeste <Your writing displays a keen intellect, capacity for communication, deep involvement and awareness in life. I look forward to when you will feel more comfortable responding to folks here... Even "just" with freshwater queries. Bob Fenner>

Cory stuck in net - 8/10/2006 Bob, <<Hey Steve, this is Lisa.>> I had to remove all my fish from my tank a week ago to remove the under gravel filter and filter out the sludge trapped beneath it.  During the process, one of my Cory's fins got stuck in the net because of that little spike that he shot out. <<Best to remove in a scoop of some kind.>> I gave him half an hour to free himself and he could not do so.  I was also unable to free him.  As a result, I cut the net away, leaving a very small piece still attached to his fin (it is one of the front side fins, I do not know the correct anatomical term for it).  The piece of net is maybe 1/8" by 1/8".  He is eating and swimming around like he is fine and there are no signs of infection or fungus, but the net is still there.  Is this an immanent health danger? <<Imminent, no. He will likely shed it in time.  If this should happen gain, gently pull him in the opposite way of the caught net.>> It looks like the net might be twisted in there.  What is going to happen? <<Watch him, and if it becomes an issue, you may need to remove with tweezers. Right now, just watch and see.  Lisa.>> Worried, Steve

Swordtail & Corydoras behavior  - 05/13/2006 Hello again, All my swords are now active and schooling. I've figured out the problem with the last female I bought. While at the pet store the other day I noticed they had a new tank marked "high finned platy". Apparently they had the red swag high finned platys and red swag swords in together, <Yikes... not smart. Can/do inter-breed> on top of that this platy is a male because he has the single pectoral fin. <Mmm, not this> My criteria for determining whether I was buying male or female swords didn't work on a platy :P I'm going to get a couple female high finned platys so hopefully the male sword will stop picking on the male platy. <A good plan> Looking at him you'd never know he wasn't a sword (other than the large top fin), he even schools with the swords but the male chases him around every once in a while and at feeding the male sword gets very aggressive toward the platy. <Yes, natural> Anyway, enough of my rambling, I've got another question for you. I originally bought 3 Corys, 1 bronze and 2 albino, I thought because they were the same species they would school. <Maybe> Well one albino died the first night, and the remaining albino and bronze would just sit by themselves all the time in the corner or under a rock. I waited a couple days to make sure no other fish were having problems in the tank and added 2 more bronze and all 3 schooled up right away but the albino still just sat there, he'd come out to eat and then go right back to his hiding spot. I had already setup a larger tank for my Betta and decided I'd do a school of albino Corys in it so I bought 2 and moved the one from my other tank to the new one, and again, he found a hiding spot and just sits there, the other 2 schooled right up. I added 3 more a couple days ago and all 5 school and ferret around the bottom looking for food but the original one just sits there. <Give it time...> If another Cory or I bother him he'll get up and start looking for food for a few sec.s and then he swims back to his spot. He'll also swim out to eat when I drop shrimp or algae pellets in. I guess I'm trying to figure out why he won't school or at least do something besides just sit there. Thanks in advance. <Takes some individuals a bit of time... Patience here. Bob Fenner>

Re: FW Q's...  - 5/5/2006 <<Hi, Marc. Tom with you this time.>> 1. That is a good idea, about the pellets. Because they eat... just not fast enough. I have algae thins for my Corys in my other tank and I suppose they will work until I run out. I just hope they will find them on the bottom because they stay in the middle to top levels of the tank. <<Marc, if your Corys are staying at the middle, or the top, of the tank, you've got a water quality problem. These fish are "bottom dwellers" and, only occasionally, venture up. Usually, it's to gulp some air (labyrinth fish) and check out what may be lying around on plants/decorations but, they don't "hang out" in the middle or, the top. That's an indication of a problem.>> 2. I just had this idea but I don't know if it will work. My mom has a pond with some nice - I actually like it... its funny - algae. Now, if I put some of my decorative rocks in her pond for awhile and then move them back into my aquarium for decoration... would that be OK? <<No, it wouldn't. Pond systems are different than aquarium systems. They're subject to different "environmental" influences and you might/probably would, introduce something into an enclosed system that would prove detrimental.>> It is green hair algae and I was wondering if it would smother my plants and get all over the glass if I move it into my tank. Will it? My Neons, Danios or rams probably wont eat it, right, because it would grow back if they do and that's fine with me. <<Let me get this right, Marc. You're looking to introduce algae, into your aquarium, that everyone else on the planet is looking to get rid of from their tanks, simply because it's "funny"? I fail to see the "humor", here, Marc. No disrespect and, admittedly, I tend to err on the side of caution with my fish and tanks but, I don't understand why someone would "toy around" with life of any kind.>> 3. One more. I have a plant that looks a lot like a Helzine (Micranthemum umbrosum). I am just not sure if it is that type of plant. <<Research this plant, Marc, and come back when you're sure. Takes less time...>> The point is that every day I come home from school and I have to yank off a ton of browning or brown, dead leaves from the base of the plant. Is this normal, because I have it in a pot of soil and it has roots. Is it dying? <<Some "preening" is not unusual though not on the level that you're doing, i.e. every day. Some plants are sold for aquariums that aren't really meant to be used for this purpose. Sometimes the aquarist just isn't sure. Might be "normal", however. Hard to know for sure.>> Sorry for all the questions. <<We ask that you do it from an informed standpoint, Marc. We don't like to "guess". (Not how we like to spend our "volunteer" time.) ;)>> Marc <<Tom>>

Spooked Corydoras Hello, <Hi there> It seems as if all sources I go to between the Pet Shops, the Internet and even Books and Articles are inevitably contradicting each other.  After going the rite of novice passage of purchasing too many ornamentation and aquarium chemicals, and other, non-essential items, I've decided to go au natural (which a friend of mine who used to work in a fish store told me to do from the beginning) and leave things be for while. <I have to agree with your friend here. The less chemical products we add to our tanks the better off our tanks are.> I started my 36 gallon bow front tank four weeks ago with two albino clawed water frogs and 6 neon tetras.  They are healthy to this day.  Two weeks ago I added three Corys.  After water checks my ammonia level is between 0 - 2ppm, PH is 7.4, my water is on the hard side (200 to 250 ppm) and I keep the temp between 75 and 80 F.  I've been told that while the PH is not optimal, it will be a problem long term and I should get it down. Otherwise, the tank is going through its cycling process just fine.  I used Stress Coat after each addition and handling of the fish.  I also have been using the Stress Zyme for the bacteria colonies.   <OK, your main concern here is the ammonia (and probably nitrites too although they aren't mentioned). This is still a relatively new tank so it's not going to be fully cycled yet but your goal is to get the ammonia (and nitrites) to a consistent 0ppm. The pH is not really something I'd be too concerned with. Yes, it's a bit high but not enough that you need to worry about and it's not going to cause any long term problems. My pH in my own community tank is kept at a pH of 7.8 and my tetras and Corys are all doing fine in it.> This past Sat, at the recommendation of a pet store owner, I added 1 tsp of PH Down to my tank each hour for three hours.  He said to do it once an hour for four hours, but I was going out and figured this could only help and the less additions to the tank, the less osmotic stress. I returned home about 6 hrs after the last PH Down tsp was added.  I turned on the light and looked in the tank to see that all 6 of my tetras lost their blue and red coloring and where a milky white and seemed kind of bloated.  The Cory's seemed to be doing fine, hanging out w/each other behind a plastic plant.  I could only locate two of the three Corys but figured he was hiding elsewhere.   <The problem with products like pH down is that they do lower the ph but then within a few hours to a day it will go right back up to almost what it was before. It takes a long time to get your ph to stay down and it's very stressful on your fish while it's happening. This fluctuation is probably what caused the color fade of your tetras.> After seeing the tetras I did a 50% water change.  That seemed to do the trick as their colors came back within 20 min. of completing the water change.  The Corys looked good too.   <Very good. Now just leave your ph alone and toss the ph down in the trash> The next day, I still could not find the third Cory.  The other two Corys however were exhibiting completely opposite behavior than they were for the past two weeks.  Originally they all hung together, swam vertically up and down quickly, in both plain water and the air bubble currents.  They were sociable and fun to watch.  They never bothered or were bothered by any of the other fish.  Now they seemed spooked.  These two Corys were hiding in either corner of the tank, sometimes alone, sometimes on top of each other. Each time I approached the tank and they saw me or other movement outside the front, they darted around as if in a panic (almost as if a predator was after them). <Probably a residual effect of the fluctuation. Make sure your ammonia and nitrites are at 0ppm and then give them a few days and they should calm down. If necessary, leaving the lights out for a day or two will help relieve some of their stress.> I figured they were behaving this way because they do good in schools and the other Cory was missing.  I decided to do an all out search (thinking I may have mistakenly thrown him out in the garden with the bucket I used for the change - never do water changes after you've had a few is the moral there... <ROTFL! I'll definitely remember that.> However, after checking the floor around the tank and futilely the garden I went back to the tank. I took out the two plastic rock formations I had and found the third Cory was stuck in the bottom of one which had a hollow back.  He wedged himself in such a way that he could not move up or back:  the only ways out. He was like this for what must be approx 12 to 16 hrs.  I freed him from this by slowly swaying the ornament in the water.  He popped out and immediately went to his friends.  Figuring he was stuck, I put the decoration back.  Within seconds he wedged himself in there again. I took him out again and removed the ornament.   <Some fish do this and removing the decoration is the only solution. Even then, they'll often find something else to hide in.> But instead of solving the problem, I got three paranoid, skittish, darting and panicky Corys on my hands now.  The behavior has been consistent for the last three days.  I see no signs of disease on their bodies, their whiskers are only getting longer, eyes are okay, gills and fins are functioning and full - if not puffed out as if in a defense mode.  These are among the hardier species, so I'm not sure what's going on.  The tank is still cycling, and when the ammonia level passed the 0-1 ppm on the chart, I added the Ammo Lock (but that was three days ago - before the Cory got stuck even). <The darting may actually be caused by the ammonia/nitrites. If these have risen again it's causing your fish some discomfort, even at the small amount mentioned. Ammo-lock helps but the best way to get your tank cycled and get the ammonia/nitrites down is water changes.> I thought perhaps one of the water frogs may have gone after the Cory (as everyone is telling me they will eat one of the tetra's any day now, but I see no sign of aggression from the frogs to them - actually, the other way around, they will poke at the frog's back, distract him, while others run in to nip at the wafer he's guarding.  If anything, the Cory's chase the frogs around in their bottom feeding ventures.   There are no signs of any aggression in my tank. <Well, the frog may eventually eat any of the fish he can catch. But the Corys should be a bit safer than the tetras because of their barbs. That's not saying it WILL happen, just that it MIGHT. Sometimes these frogs (and other species) live peacefully with fish for ages, other times they'll eat every fish in the tank.> I did make another change:  I added twelve more neon tetras.  I figure cycling for an appropriate volume of fish, given my other parameters, should be the priority, ph being second as it's not at such a highly noxious level. I've got the ammo lock on hand in case of anything and am checking the ammonia and ph daily. <That's a lot to add at one time so keep up with your testing and water changes. Rely on the water changes the most and only use the Ammo-lock if it's an emergency.> Thanks for reading all that but I wanted to be sure to convey all the detail. Here are my questions: <Thank you for being thorough> What is going on with my Cory's?  I was thinking that I should add 2 or 3 more as all info says they do better in schools of 5+.  But I don't want to add if there's any diseases, yet there are no signs of any.  Could this behavior have developed because they are "under - schooled" (no pun intended)?  Or could they be traumatized by the removal and replacement of the ornaments and the large water change?  But the others seem fine. <I don't think there are any diseases but don't add anything else until the tank is fully cycled. Then you should be able to safely add another 2 or 3 Corys.> Am I right in my priorities:  cycling first and ph second? (given my PH is on the low side of high) <Definitely. Like I said above, don't even worry about the ph at this level.> I was thinking of adding the PH Down 1 teaspoon per day until I've achieve 6.8-7.0, but am not sure it that's what caused all the stress to begin with. <Nope, toss that stuff in the trash. Your fish are better off in a high but stable ph than in a lower fluctuating one.> I added 12 more tetras yesterday and everything seems fine.  The frogs seem to be a little annoyed at the increase no.'s of tetra's which swarm around them and their wafers, but are otherwise fine.  The Cory's are still darting, spooked and skittish, but this morning they came out to feed - tentatively and cautiously (as if watching for something) in the center of the tank.  My wife just called me now to say that they are still "going absolutely crazy".   <You may notice your frogs going after the fish a bit more now that there are more of them in there. And just give the Corys a bit of time, they should calm down.> so...what's happening with these Corys?  Also - in order for them to school, am I obligated to get the same species of Cory or can I get three of a different species and still have a school of six? <They will probably school with other types, most of them will.> Also - what additional fish (colorful - as per the wife) would you recommend adding (down the road, of course) to this hopefully successful community tank? <Some options would be: Platies (these are livebearers so get 2 males unless you want tons of babies that will get eaten by the other fish and frogs), some of the less aggressive Barbs. I like the Cherry Barbs and the Rosy Barbs although the Cherries turn more brown as they get older where the Rosies turn a gorgeous red and green, or some of the other Tetra species like the Cardinals (basically larger versions of the Neons), head & tail lights, Penguins (these can be a bit ornery but not too bad), etc. Stay away from any fish that gets more than about 2'-3' long because your Neons will become food for them. A great place to look at pictures of different fish species is at http://www.wetwebmedia.com  in the photos section and also http://www.fishbase.org > Thanks in advance for your help CJ <You're welcome! Ronni>

Three Line Cory Catfish question Thank you so much you have helped me in the past, I hope you can again. This Cory catfish started acting funny, he is constantly going up and down, but not for the usual gulps of air, just blindly bumping into everyone else up around and down. <Mmm, may well be interacting with its reflection... in your aquarium walls. Corydoras Catfishes are extremely social... do best in groupings> All the water parameters are ok and all the other fish are ok too, so is one other Cory catfish. Do you have any idea what this might be, I figured if it's a parasite or something the other fish will be affected. Thanks again for your time and your insight. <If you have room, I would add another two or more of this species. Bob Fenner>
Re: Three Line Cory Catfish question
Thanks for the speedy reply. I wanted to add that this Cory bumps into other fish swimming while he flutters/scutters like on a roller coaster along the glass. <Not atypical> Zooms up and down however he slows down enough to not hurt his barbels when close to surface, but when in water he bumps into other fish, did I say that twice. <Yes, yes> He has 1 buddy and he completely ignores him, the other just works all the time, rarely I see him tries to follow other but there' no pattern and goes back to working. I do have reflection on the glass but do you think that might be the cause with him bumping around? Thanks for your patience. By the way Happy New Year! <Yes, and thanks much. All will likely be fine in time. Bob Fenner>  

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