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Corydoras breeders:

I have recenty run into a little trouble with spinal deformity in my Corydoras fry. I have never "mass produced" fry before and am stumped.
Is this a normal/regular/expected problem and what can I do to fix it?

Thanks, in adavance,
Kevin Korotev
Milwaukee, WI USA

Unfortunately, I have this problem with Aeneus Cories. I've been keeping a diary on their progression, or lack of it. I think their parents were overbred. It's a very sad situation. They are no longer fry, but almost 1 year of age. But, they still look like fry. All of them have lost their barbels.

The Paleatus Cories, who started breeding around the same time, are just the opposite.

The (4)Aeneus parents and (4)off-spring are in a 29 gallon tank with 4 Cherry Barbs. The Cherry Barbs have developed bent spines as well.

So, I guess I'm asking as well. The Aeneus parents looked very healthy. They had Ick early in their lives. But, the Paleatus did, too. Is there any way to tell if potential breeding stock is overbred?

I have never had a problem with spinal deformity in Cory fry. I know that Ian agrees it is important to start with good stock when breeding Corys or any other fish. Aeneus probably the most common and popular of Corys is very inbred, the same can be said for popular breeds of dogs who experience many health problems. It wouldn't be a bad idea to start with some wild aeneus if they are available in your area.

Mark

There are several factors that can give you deformity problems and it's not always down to genetics. Agreed inbreeding is the major cause, but I have found water conditions at the time the spawning takes place can and will have an adverse effect. I was breeding a group of wild C65's and as I always do, I checked the water parameters imediatly after the spawning only to find a nitrite level of 30 ppm. Everything seemed fine other than that, the fry all hatched and seemed to grow quite well, but as the fry grew larger they started to show a deformed dorsal fin. The deformity became more and more exaggerated as they got bigger, also there was a bend in the body at the caudal peduncle.

If your fish have been producing good young up until now this may be the cause. I know you guys that have heard my talks will have heard me repeat the need to record everything that happens because it's times like this when the information is invaluable.

Hope it helps.

Ian

I tried to take pictures this morning. The Aeneus absolutely panicked! I've never seen this. What I did was set up the camera on the tripod and left it there. Maybe they'll get used to it.

The fry started out growing incredibly fast. They had beautiful barbels. The first sign of trouble was the barbels falling out. But, there was no substrate in the net breeder where they hatched. (The Paleatus hatched the same way and have lush barbels)I've noticed some of the surviving offspring have very small mouths. It seems they struggle to eat at times. I think they're starving. I just purchased two more 10 gallon tanks. This would be a total of (3) 10 gallon tanks. This group is in a 29 gallon tank now. I have a 75 gallon tank, too.

I've thought of separating everybody. Take the offspring into a 10 gallon tank. Take the parents into another 10 gallon tank. Take the Cherry Barbs into a 10 gallon tank and raise plant cuttings in each of the tanks. The 29 gallon tank is lightly planted. The current substrate would need to be changed to accomodate heavier planting. It's just gravel. The 75 gallon tank is moderately planted tank and getting lusher.

I've had the Aeneus/Cherry Barbs together since December 2004. They seem very out of sorts. I don't want these fish to reproduce, but I want them to have comfortable lives. What do you think about separating them into smaller groups?

The one on the lower right is more than 10 months old:


At first, I thought this male/parent was injured. In retrospect, I think he had a birth defect, too. This was one of the first fish I ever bought.


Here's one of his offspring:


This shows the small mouth on another:

Personally I think your main problem is substrate, the gravel in the pictures is enormous, fine smooth sand would be far better. Also you say that fry were raised in a net trap, this I think would have started the problem with the mouths and barbels. The net would not retain much food is any and the fry would be constantly working the mesh looking for food particles. I cannot see what I would call genetic faults, the damage was caused early in life and I am afraid to say cannot be reversed.

Ian

My fish is the Corydoras aeneus sp. cf "Black". I have heard that the very color is the biggest obstacle to 100% healthy fry as there is a lot of energy spent in early growth on melatonin production?
I have also heard this fish is ALWAYS inbred as it no longer comes from the wild? My supplier swears they are wild fish...but early in the purchase discussion I swear I can remember him saying something about Europe as the source?

All new to me,
Kevin

There are two strains of so called "Blacks" One from Venezuela, these are actually dark reddish drown, with slightly lighter fin colour, the real dark almost black strain was developed in the Czech Republic and may very well have been from the Venezuelan strain. The Czech strain are not so strong and do throw some misfits if conditions are not perfect.

Ian

I've ordered sand and Flora Base. The Paleatus roll around in the Flora Base. I'm already picking out what little gravel there is in their 75 gallon tank.

I'm going to go ahead and separate them out into 3 groups: the Cherry Barbs get a 10 gallon. The parent Aeneus get a 10 gallon and the offspring will get their own 10 gallon. The tanks were on sale for $10 at a LFS that just opened. It'll take me a few weeks to get it set up, but I think they'll be more comfortable: 4 fish in each with moderate planting. The 29 gal was the first tank I set up on my own. If you think I'm ignorant now, you should've seen me then! I feel horrible about all of this. I hope to learn and give them a better home.

Here are the three 10 gallon tanks. They're adjusting to their new homes. All chemistry levels have been stable for a few days now. I've got the Cories in the tank on the right. The Cherry Barbs are in the middle. I'll see how all the Cories do together. I have the third tank waiting. Just taking the Cherry Barbs out has settled them tremendously. So much for them being a "community species." I think it was a very bad mix. All three have sand and Flora Base. The plants are cuttings from the 75 gallon tank.



The 29 gallon tank is broken down. I'm going to redo it at a later date.

DELETED

Thanks. I only hope they look this good in a month.

Hope this isn't getting off the subject, but I was interested in what was said about Melatonin production in Corys.
I have recently raised my first batch of C. paleatus and one of them is quite dark, though from grey parents.
He is a cute little fella with his pale eyes, but has not grown well and has an upturned tail. (Other caudal deformities I have seen in fish have been downturns).
In horses and cattle production of black pigment requires a lot more copper in their diet. This isn't much help in raising dark Corys though is it?
I have another dark coloured C.paleatus (unrelated) and I am wondering whether it is a good idea or not to breed my little black one with the wonky tail - it doesn't look horrendous but is definitely upswept.
Any theories? How common are dark C. paleatus anyway?
Jan