At Least Half The Cory's I Bring Home Die. Getting Really Disgruntled...

So a few days ago I finally came a crossed Adolfoi Corys, after searching for months. I was extremely excited and instantly picked up 6 of them. Also, from the same place I got 3 Hasbrosus Corys (to add to my current 5). It has only been two days since I have brought them home and 4/6 of the Adolfoi's have died, but the three Hasbrosus are doing amazing in the same tank, and I am at a loss. I am extremely disheartened by it. All of these corys had been placed in a seasoned 10g with plenty of flame moss and a well cycled sponge filter.

All of the Adolfoi's were about 1/2" long, which I know is small, but I am okay with growing out fish. The Hasbrosus were a bit over 1/2", but given they are a pygmy-type cory, they seem to be about 2 months off of breeding age.

With the Adolfoi's I purchased 6, which they had been in the bag about 5 hours prior to getting them home as it was a day trip I had made to go look at a bunch of stores. I kept them all inside of a cooler and ensured that they wouldn't be bouncing around in there.

One of the 6 had died even before I got it home. The second I noticed had some fungus on it's head along with labored breathing. When I noticed this, I did a waterchange and dosed the appropriate amount of Ich-X and erythromycin, specifically to combat any type of fungus growing and if any bacterial infection would result of a wound from the fungus. For the cory in question, I have seen a quite a few sick fish (I work in a fish store), and can tell when it's unlikely for one to make it, and this was that case. I considered 4/6 surviving to be alright odds, but still I was quite sad. I then woke up the following morning to find not only the one I noticed sick dead, but two of the Adolfoi's dead. This now leaves me with three left, but by the end of the day I found another dead as well. I had fed the fish yesterday frozen baby brine shrimp and watched them eat. 4/5 remaining had eaten except the one I knew was on it's way out.

At this point I am pretty much at complete loss. Out of 6 cory's they all looked very good from the start, but they have been crashing. I decided tonight the concentration of meds may be too much so I performed a 40% waterchange. I now have 2/6 Adolfoi's left and I am truly hoping for the best. All of the Hasbrosus are doing amazing with great color and activity, but the Adolfoi's seem to not be doing so hot.

This really doesn't end here. This is just my recent experience. At the store I work at our Cory survival rate is extremely pitiful. Note: I did not get cory's from the place I work, but another shop. I can recall a specific instance where we had ordered 24 Pygmy cory's, 22/24 arrived dead, all less than 1/3" long, and the following two died shortly after arrival. We always try to bring in Sterbai Cory's, where about 50% of them die within 5 days of arrival. The same goes for Panda cory's. I have finally managed to get myself a group of 5 sterbai's at home I am growing out, but I had to purchase about 15 to get these results. I love my cory's, but I hate bringing them home for them to simply die without any symptoms of which I can tell.

I understand that the ones that came into the store I work at is probably from poor wholesale care, but the Aldolfoi's I had gotten were locally bred, not local to me, but to the store. My assumption is that the cory's were simply too young to be sold and transferred to my water system. If I had to age them, I would guess about 2.5-3 months old, really close to 1/2" long.

What I have noticed is that the corys that do make it in systems for a while tend to last for a long time. It is like the trend I see with Otocinclus. Once they make it passed that two week mark you are good, but until then it is sheer gambling. I bought a pair of skinny paleatus cory's that were hiding in a system at my work for at least a month and I still have them, doing amazing, I had no issues whatsoever.

If anybody else has any idea of what I could be doing wrong or any insight, I would greatly appreciate it. I have been trying to hold off on buying every fish I wanted recently, but these I made an exception for. Its really put a damper on things and I wish that I could know what's going wrong.

For those of you who care about the "emergency template"
Tank- 10g
Filter - Sponge filter
pH - 7.5
Ammonia-0
Nitrite-0
Nitrate- <10PPM

The tank has been running for at least 6 months with an active population of snails and a good bit of flame moss.


If anybody has any questions to help me I would really appreciate it! Any feedback would be greatly appreciated as well! Thank you for reading!

 

So a few days ago I finally came a crossed Adolfoi Corys, after searching for months. I was extremely excited and instantly picked up 6 of them. Also, from the same place I got 3 Hasbrosus Corys (to add to my current 5). It has only been two days since I have brought them home and 4/6 of the Adolfoi's have died, but the three Hasbrosus are doing amazing in the same tank, and I am at a loss. I am extremely disheartened by it. All of these corys had been placed in a seasoned 10g with plenty of flame moss and a well cycled sponge filter.

All of the Adolfoi's were about 1/2" long, which I know is small, but I am okay with growing out fish. The Hasbrosus were a bit over 1/2", but given they are a pygmy-type cory, they seem to be about 2 months off of breeding age.

With the Adolfoi's I purchased 6, which they had been in the bag about 5 hours prior to getting them home as it was a day trip I had made to go look at a bunch of stores. I kept them all inside of a cooler and ensured that they wouldn't be bouncing around in there.

One of the 6 had died even before I got it home. The second I noticed had some fungus on it's head along with labored breathing. When I noticed this, I did a waterchange and dosed the appropriate amount of Ich-X and erythromycin, specifically to combat any type of fungus growing and if any bacterial infection would result of a wound from the fungus. For the cory in question, I have seen a quite a few sick fish (I work in a fish store), and can tell when it's unlikely for one to make it, and this was that case. I considered 4/6 surviving to be alright odds, but still I was quite sad. I then woke up the following morning to find not only the one I noticed sick dead, but two of the Adolfoi's dead. This now leaves me with three left, but by the end of the day I found another dead as well. I had fed the fish yesterday frozen baby brine shrimp and watched them eat. 4/5 remaining had eaten except the one I knew was on it's way out.

At this point I am pretty much at complete loss. Out of 6 cory's they all looked very good from the start, but they have been crashing. I decided tonight the concentration of meds may be too much so I performed a 40% waterchange. I now have 2/6 Adolfoi's left and I am truly hoping for the best. All of the Hasbrosus are doing amazing with great color and activity, but the Adolfoi's seem to not be doing so hot.

This really doesn't end here. This is just my recent experience. At the store I work at our Cory survival rate is extremely pitiful. Note: I did not get cory's from the place I work, but another shop. I can recall a specific instance where we had ordered 24 Pygmy cory's, 22/24 arrived dead, all less than 1/3" long, and the following two died shortly after arrival. We always try to bring in Sterbai Cory's, where about 50% of them die within 5 days of arrival. The same goes for Panda cory's. I have finally managed to get myself a group of 5 sterbai's at home I am growing out, but I had to purchase about 15 to get these results. I love my cory's, but I hate bringing them home for them to simply die without any symptoms of which I can tell.

I understand that the ones that came into the store I work at is probably from poor wholesale care, but the Aldolfoi's I had gotten were locally bred, not local to me, but to the store. My assumption is that the cory's were simply too young to be sold and transferred to my water system. If I had to age them, I would guess about 2.5-3 months old, really close to 1/2" long.

What I have noticed is that the corys that do make it in systems for a while tend to last for a long time. It is like the trend I see with Otocinclus. Once they make it passed that two week mark you are good, but until then it is sheer gambling. I bought a pair of skinny paleatus cory's that were hiding in a system at my work for at least a month and I still have them, doing amazing, I had no issues whatsoever.

If anybody else has any idea of what I could be doing wrong or any insight, I would greatly appreciate it. I have been trying to hold off on buying every fish I wanted recently, but these I made an exception for. Its really put a damper on things and I wish that I could know what's going wrong.

For those of you who care about the "emergency template"
Tank- 10g
Filter - Sponge filter
pH - 7.5
Ammonia-0
Nitrite-0
Nitrate- <10PPM

The tank has been running for at least 6 months with an active population of snails and a good bit of flame moss.


If anybody has any questions to help me I would really appreciate it! Any feedback would be greatly appreciated as well! Thank you for reading!

Hey! So my first foray into owning corys was very similar. I had been in the hobby for at least a year, and had maybe only ever lost 1 fish during the first 2 weeks. I bought 6-8 sterbai Corys and I believe lost every one. Based on my research, corys can be deceptively sensitive and do not handle the journey from wholesaler/breeder to the eventual owner very well relatively speaking. I think it’s important to look for really high quality Corys, ideally the older the better because my experience has been very similar to yours. Also, try not to be discouraged because it isn’t you that is doing anything wrong granted you are purchasing healthy looking fish and doing the acclimation process correctly.

 

Hey! So my first foray into owning corys was very similar. I had been in the hobby for at least a year, and had maybe only ever lost 1 fish during the first 2 weeks. I bought 6-8 sterbai Corys and I believe lost every one. Based on my research, corys can be deceptively sensitive and do not handle the journey from wholesaler/breeder to the eventual owner very well relatively speaking. I think it’s important to look for really high quality Corys, ideally the older the better because my experience has been very similar to yours. Also, try not to be discouraged because it isn’t you that is doing anything wrong granted you are purchasing healthy looking fish and doing the acclimation process correctly.

Yeah, I feel as if I could take a bit more precaution with cory's in specific when it comes to acclimating. With most fish I have owned I pretty much temperature acclimate for 15-30 minutes, then put them through a net and into the tank. In prep I normally do a waterchange on a tank before I get fish home so I know nitrates are low. Given my experience, I feel like it may be best for me to do a type of drip acclimation or partial w/c acclimation to more gradually incorporate them. The only time I really just plop and drop is if its something like a zebra danio, or if I am moving between tanks within the fishroom. All of the tanks are the same temp due to room heat.

 

Besides the smaller species this in completely different than my experiences with Cories.

I think one issue could be that the Corys were starved OR on a onesided / wrong diet with the wholesaler. A condition I call "Algaewaferitis" cause even wholesalers and several LFS's feed them algaewafers.
Lacking the right food causes all kibds of problems.

Adolfoi often are wildcaught so just like Otos maybe not used to any of "human" made food and ptobably sensitive to changes in Ph- / hardnessdifferences etc....

I try to get my corys from local hobbybreeders.

 

Besides the smaller species this in completely different than my experiences with Cories.

I think one issue could be that the Corys were starved OR on a onesided / wrong diet with the wholesaler. A condition I call "Algaewaferitis" cause even wholesalers and several LFS's feed them algaewafers.
Lacking the right food causes all kibds of problems.

Adolfoi often are wildcaught so just like Otos maybe not used to any of "human" made food and ptobably sensitive to changes in Ph- / hardnessdifferences etc....

I try to get my corys from local hobbybreeders.

I know Adolfoi are usually wild caught, and I would love to get my corys from local breeders too, but there is the issue and thus my passion for corys. Litereally nobody around me breeds corys. When I say nobody, I mean nobody. The Adolfoi I got were actually hobbiest bred, but that is 3 hours away from me. None of them looked unhealthy or lethargic in the tank either, hence my issue. When I feed my corys I usually feed either frozen baby brine or bloodworms, but I cannot attest to what they had been fed before.

Ultimately my goal is to become that cory breeder because I do love the little fellas, but getting the breeding stock is proving a real challenge. The only corys that I have breeding for me currently are pymaeus and schultzei-black. I really want to get ahold of similis corys and a nice group of Adolfoi's, but when things like this happen it is really hard to want to go get more, especially when its only one place I have seen them.

 

A friend got wild caught C. adolfoi last year. They seem to be very sensitive to pH over 7. Said friend got quarantined with COVID and was unable to renew the peat he uses to keep blackwater conditions, the pH went from 6.0 to 7.8 within 48h, which usually is slow enough for most fish to adapt, but it knocked out almost the whole school he had except one.
All other fish (emperor tetras, angels, parotocinlus) in the tank were completely fine, only the breeding pair of Angels ate their eggs and stopped spawning for a week.

So I would presume this here is a multifactor thing.

 

Sold C.adolfoi often appear to be tankbred C.duplicareus btw

 

Sold C.adolfoi often appear to be tankbred C.duplicareus btw

Yeah, I know they look really similar, but I wasn't very concerned if I got duplicareus versus adolfoi's, it wasn't really going to change how I cared for them. I have always found that stable water conditions are whats best for most fish. The only fish I really haven't been able to keep is because they crash is Rams.

As an update today, all 6 of the supposed Adolfoi corys have died, but the three hasbrosus corys are doing amazing. Honestly I am very shocked by this and never thought this would have happened. Judging by how the hasbrosus are doing makes me think it is something that isn't from me, but rather a pre-existing condition or problem with the fish. I might be wrong here, but how else would one species die off so quickly and another thrive? At this point I am pretty upset, but rather would like to use it as a teaching experience for myself as this is something I really want to have success with. This is more of a situation of 'What could I do better next time?'

I suppose I could do a more careful acclimation of the fish prior to introduction, and I could add some driftwood to the tank I plan to put adolfoi's in for the tannins. Over time I would waterchange them out and slowly bring up the pH and maybe?

 

Not that it helps other than to say "you're not alone", but I've also recently seen something that seemed rather species-specific even within the Cory genus, and unusual.

I recently had my entire population (25+, I'd had them almost 2 years and they'd spawned many times, at least 10 of that shoal were born in my tank) wiped out over the course of a couple of months; and I still have no idea what (disease, parasite) killed them.

Whatever it was came in with a few new ones I'd added for genetic diversity. They'd been QT'd by the seller for 2 weeks and by me for 1 (since I knew the seller, had bought from him before; no reason to doubt that they'd already been through 2 weeks of QT.) No issues during QT, nor for a couple of weeks after adding them.

And then they started dying. One at a time for the most part, occasionally 2 or 3. Some just stopped eating. Some acted like they were having difficulty breathing shortly before they died, but no other symptoms. Some had lighter patches that looked like columnaris infection, but nothing that I tried by way of treatment (individually or in the tank) made any difference.

Meanwhile, I'd also brought home some peppered cory eggs on a leaf, my pair at work had spawned and the hastatus tank was a good place to hatch them (also before I knew this was going to happen.) The babies hatched out into all this, and...they weren't affected at all. All hatched, all survived, 5 were given away when old enough and 2 of them are still in that tank right now. (I assume the ones I gave away didn’t carry anything with them; I didn't hear anything about any issues later.)

But when I transferred the sole remaining healthy hastatus cory (it was one that had hatched after nearly all the adults had died) into a tank with a few habrosus corys, with a salt/MB bath and acriflavine treatment in between just in case...all the habrosus corys died within days (they weren't new, I'd had them for months. The tank was mature and parameters fine).

Meanwhile the sole remaining 'healthy' hastatus is still showing no symptoms of illness or parasites at all. It's looking and acting very forlorn because it's all alone - which is why I'd put it in with the smaller of my habrosus shoals in the first place (hastatus not being available except for a few months every year.)

So I'm left with 2 tanks, one with 2 young and outwardly healthy peppered corys, and another with a single hastatus cory. I don't dare move the fish nor add to them after what happened to the habrosus corys. And I still don’t know what actually is wrong with either tank. A very resistant form of columnaris, or a resistant parasite I can't see and the columnaris was secondary...?

I'd have to get a necropsy to know for sure, and there aren't any registered fish vets within 300 miles of me, nor are any of the local college/university biology departments interested in doing one (I actually asked them, as well as local veterinarians.)

I've never run across anything like this; that seemed to only affect some species and not others, with nearly 100% mortality of the affected species, and apparently transmitted by a fish that has survived it and never showed any symptoms of being ill.

Don't know, but I can relate to the frustration. Seeing nothing but sick swordtails for sale is what got me into breeding those originally as well. I still see sick ones in almost every store, all the time, for years now. It doesn't seem like Europe is seeing the same levels of sick/fragile fish that we are, not sure why unless it's only happening with/at our importers/wholesalers.

 

Don't know, but I can relate to the frustration. Seeing nothing but sick swordtails for sale is what got me into breeding those originally as well. I still see sick ones in almost every store, all the time, for years now. It doesn't seem like Europe is seeing the same levels of sick/fragile fish that we are, not sure why unless it's only happening with/at our importers/wholesalers.

Yeah I can really relate to the story. I can agree with the genetic diversity thing here, as if what they told me was true about them all being from a local breeder, they could all be inbred and thus weaker in general.

 

Yeah, I know they look really similar, but I wasn't very concerned if I got duplicareus versus adolfoi's, it wasn't really going to change how I cared for them. I have always found that stable water conditions are whats best for most fish. The only fish I really haven't been able to keep is because they crash is Rams.

As an update today, all 6 of the supposed Adolfoi corys have died, but the three hasbrosus corys are doing amazing. Honestly I am very shocked by this and never thought this would have happened. Judging by how the hasbrosus are doing makes me think it is something that isn't from me, but rather a pre-existing condition or problem with the fish. I might be wrong here, but how else would one species die off so quickly and another thrive? At this point I am pretty upset, but rather would like to use it as a teaching experience for myself as this is something I really want to have success with. This is more of a situation of 'What could I do better next time?'

I suppose I could do a more careful acclimation of the fish prior to introduction, and I could add some driftwood to the tank I plan to put adolfoi's in for the tannins. Over time I would waterchange them out and slowly bring up the pH and maybe?

I think we can always second guess ourselves but sometimes these things happen and the reasons will remain a mystery. For example....I purchased 10 green lasers, 8 eques 9 Adolfos, 14 similes, 8 trilineanis and 9 milinis from my awesome local fish store and lost none. Granted I always buy them after they’ve been at the store for a week at least and I put them through an ich-x, general cure and prazi-pro regiment once they are in my tanks. But, the orange Venezuelans that I also got from my lfs keep crashing on me. Of the 6 that I bought from the exact same lfs and having gone through the same meds regiment, I only have two of the 6 left, though they are really fat and robust. So who knows? Life is precious and I hope you enjoy your dwarf cories and try again with the Adolfos. They are one of my favorites and I can see why you are feeling down. But I bet it’s the fish and not what you’re doing. They may have poisoned themselves in the bag on the several hour trip home....

 

I dont know if this is true, or if it could have anything to do with it, but I read recently that cories when stressed ( eg when bagged or transported) release a toxin that can be harmful to other fish, and that for this reason they should be bagged individually. Is it possible that anything like this is happening?

 

I dont know if this is true, or if it could have anything to do with it, but I read recently that cories when stressed ( eg when bagged or transported) release a toxin that can be harmful to other fish, and that for this reason they should be bagged individually. Is it possible that anything like this is happening?

The active release has only been proven for few species like Corydoras (former Brochis) splendens.
I'm not positive all species named here with problems fall into that category. I would actually doubt that, since then many people would have to report similar things regularly.

 

The active release has only been proven for few species like Corydoras (former Brochis) splendens.
I'm not positive all species named here with problems fall into that category. I would actually doubt that, since then many people would have to report similar things regularly.

I agree it is probably unlikely, it was just a thought...

 

It’s just a thought for me too. I bought 8 sterbais from Dan’s fish in Get Gills and they arrived in separate container bags. In one of his videos Dan stated that when he switched to single-bagging his cories to be sent to his customers, the DOA rate for the cories went way down. So I’m not sure either way but who knows.