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Alright so I have a couple questions.

This was really worrying me last night and prompted me to make an account here, but it took a while for the admins to approve my account so I could post. One of my little cories seemed to be having trouble staying at the bottom last night. He was one of 3 new additions that I added to the tank the previous night. He couldn't seem to rest at the bottom like all of the others, so he was having to constantly swim downward. The moment he would stop swimming he would slowly start floating upward. He didn't seem to have balance issues, he stayed upright just fine and wasn't swimming in a corkscrew fashion or anything, just floating upward with his body still level with the sand. This had me worried because all of the searching I did suggested that cories don't usually recover from this type of problem. Eventually however, he figured out that he can wedge himself between one of his little cory friends and a plant stalk to keep himself down. He rested like that for a couple hours and then seemingly was able to stay at the bottom with no assistance again! Maybe he just had a little gas bubble or something and it went away? I didn't feed them last night just in case, because I read fasting them once can sometimes get rid of bloating. I came down to see the tank today scared that I would find him dead, but luckily all cories are alive and nobody is floating

So the question is, what was that little guy dealing with last night, and is it contagious? I bought him with 2 others the night before last because when I bought my original 5 they were all that was in stock so I had to wait for another shipment to get to 8 which was my original plan. I was desperately hoping whatever was going on with him wouldn't spread to the others, and was very close to pulling him out to put him in a little quarantine tank until he eventually improved.


My next question is not an emergency luckily. I've noticed that my 3 new additions are much more tan colored than my 5 others. The old 5 are grey/white with black spots, and the newer ones are more of a tan color. Here's a picture where you can see the two closest to the camera stand out. Is the tan color a bad thing or is it just the way they are colored? I want to make sure they aren't malnourished or something.

Lastly, I know it's uncommon to find real Corydoras Julii in stores, so I'm assuming these are Trilineatus, but it is so hard to tell based on the descriptions on the internet. I bought them at petco labeled as juliis but I figure they probably aren't the real ones. Anyone able to confirm one way or the other?

I totally forgot to include in my post, at the time of my worries, PH was 6.4, Ammonia 0ppm Nitrite 0ppm Nitrate 20ppm, Temperature 76*. I do not have a hardness test kit so idk what those were.

Hi Lettuce,

First of all, welcome to PlanetCatfish, and best of luck with your Corys.

Regarding your questions, I'm sorry but I can't offer any insights regarding the swimming behavior (hopefully someone else here with more experience can help with that), but I can give you some help with your other questions.

About the color variation evident in the photo you provided, it looks normal to me and should not be a concern. I have several

Corydoras trilineatus

(some from Petco, like yours) and they too show some color variation. Even the photos of trilineatus shown on this website differ a little bit in the overall body color. The color that I worry about on a fish is red where it doesn't belong, because that is often a sign of disease.

And as to the species identity of the fish in your photo, they appear to be trilineatus not

Corydoras julii

. As I learned the difference, true julii have a forehead covered with black dots, and the mid-lateral black line is relatively faint or broken up. By contrast, most trilineatus have a reticulated pattern of interweaving short black lines on the forehead (like a maze), and the mid-lateral black line is more prominent. From your photo, your fish are relatively small (I'm guessing 3/4 to 1 inch in length), so the forehead color pattern is not fully developed, but it is already clearly evident that your corys have the reticulated coloration.

Without wanting to sound preach-y, I would like to say that in my humble opinion, it is never a good idea to add newly purchased fish directly into an established aquarium with other fish; it is always a good idea to bring your new fish home to a quarantine tank (even if the fish "look" healthy when you buy them) and leave them there for at least a couple of weeks to make sure they aren't carrying ich or some other disease. And I would say this rule is especially true for fish purchased from major chain stores, which (in my experience) don't usually provide the best care for the fish they have for sale.

I hope that helps.

Cheers, Eric

Yeah in the future I will probably use a quarantine tank. I have a 3 gallon jar but no heater so I was reluctant to put them in there in case the water got too cold. I kind of just figured this time since they were in the same tank at petco and looking healthy it wouldn't be an issue. I checked all of their other tanks for unhealthy looking fish and they were all fine. In hindsight it was probably a bit risky.

Now after observing that little cory for a couple days, I think he might just be a very active little guy. He's still swimming all over the tank and going up near the surface, but he has no trouble laying back down at the bottom when he wants to. I think he's just more adventurous than the others, as he goes off alone a lot. The tank is on my desk right next to me, and most of the time He's swimming around right next to my face looking at me. I think he's just a curious little guy.

https://www.youtube.com/watch?v=mUDoSSC ... e=youtu.be

There's a video of him hanging out by me in the front corner of the tank, when the rest of his crew were in the back resting

I watched the video. Your Cory looks pretty good, actually. It may be that the fish just had to go through an adjustment period in your tank. Unless its behavior changes, or the floating behavior comes back, I wouldn't be concerned.

Cheers, Eric

The floating often is caused by new Corys (in stress) will take a bigger gulp of air than normally (secundary breathing-system).
To my knowledge Trilineatus are found over a widespread aerea and will therefor often be different in shape, color, markjngs aso. The one in front of the tank seems to have quite an odd shape to me. But when they are doing great, why worry ?

CoryfanAad wrote:The one in front of the tank seems to have quite an odd shape to me.

I saw that too, but I'm thinking that this is more likely to be a simple visual distortion in the photo caused by the camera angle and the fact that this fish happens to be closer to the front pane of glass than are the other corys, rather than an actual deformity in the fish.

CoryfanAad wrote:But when they are doing great, why worry ?

Exactly true.

Yeah the one in the front's head is not shaped like that, it was just a weird angle with some refraction I suppose.

Hi,

I would agree that you most probably have C. trilineatus, they look rather typical.
Although the difference is most cases like Eric wrote there are expections:
C. trilineatus with only spots on the head, C. julii with a reticulated pattern, in C. trilineatus I even had one specimen without the midlateral line on one side.
They are very flexible with respect to pattern and we can find lots of corys with similar patterns in many river systems between south-east Brazil, the Guayana shield and Peru and Bolivia.

To ID these corys for sure just based on pictures is close to impossible.
The best would be to find out the origin of the corys. C. trilineatus is imported in huge quantities (mostly) from Peru whereas C. julii is imported only from time to time from south-east Brazil.
I've been told that C. julii spawns during the night whereas C. trilineatus spawns during the day (I can confirm the latter case). But who knows if this is always true...

Cheers,

kamas88 wrote:I've been told that C. julii spawns during the night whereas C. trilineatus spawns during the day (I can confirm the latter case). But who knows if this is always true...

Unfortunately, some species don't perfectly replicate their natural breeding behaviors in captivity, so even if this is true, it might not be seen in the aquarium. My trilineatus spawn at night sometimes... Of course that could mean I have Julii, although I seriously doubt it. (The "collection data" I have on my fish is woefully inaccurate-I collected mine at Petco and PetSmart, LOL, and who knows where they get theirs (I suspect captive bred)).

Cheers, Eric

kamas88 wrote:Hi,

Although the difference is most cases like Eric wrote there are expections:
C. trilineatus with only spots on the head, C. julii with a reticulated pattern, in C. trilineatus I even had one specimen without the midlateral line on one side.
They are very flexible with respect to pattern and we can find lots of corys with similar patterns in many river systems between south-east Brazil, the Guayana shield and Peru and Bolivia.

To ID these corys for sure just based on pictures is close to impossible.
The best would be to find out the origin of the corys. C. trilineatus is imported in huge quantities (mostly) from Peru whereas C. julii is imported only from time to time from south-east Brazil.

I am considering aquiring C. Julii from a source that imported them from Columbia. Any chance they are true julii or just C. Trillineatus with spotted pattern?

Here is a picture of the fish from the seller:

Hi,

with the origin Colombia we can IMHO exclude C. julii.
C. trilineatus is described from Peru, Rio Ambiyacu. I have not found this river on a map but I'm quite sure that this is northeast from Iquitos. Which means not too far from Colombia. So it might be C. trilineatus or a closely related from.

Cheers,

While researching Cope's 1872 papers that describe C.trilineatus, C.acutus, C.amphibelus, C.armatus, C.ambiacus and others I discovered that the Rio Ambiyacu is now known by the name "Rio Ampiyacu". For whatever reason Google does not show this river in their Google maps (street view) mode. It does however show up if you look at the satelite map. Scotcat.com has a map on their website that shows the Rio Ampiyacu: