Improving C.schultzei(Black)

rmc · Post by **rmc** » 25 Jun 2013, 14:13

I'm working with a group of young Corydoras schultzei right now, the "Black" type. I have just started getting eggs in the past few weeks and I've been reading up on them as much as possible. A lot of what I've read states that the "Black" C. schultzei's need to be "heavily" culled which I'm guessing is because of deformities caused by line breeding and a lack of genetic variety. My question is has anyone tried to breed the "Black" variety back to standard C. schultzei? Would this improve the line? If anyone has done so what were the results? Were there any Black fry, or would they just "carry" the gene?

CoryWally · Post by **CoryWally** » 25 Jun 2013, 14:32

I don't have a problem with poor quality offspring. I have found they breed true with no deformities from hundreds I have raised.

I'd be interested to see the source of info suggesting they need to be culled.

Cheers,
Mark.

rmc · Post by **rmc** » 25 Jun 2013, 14:53

Hi Mark,
Thanks for the fast response! The fact that you're not having too many problems gives me more hope! I know I read this in a few places, but here's a link to the fastest source I could find:

http://www.aquaboards.com/archive/index ... 68252.html

read the post by coryologist.

Cheers,

Rob

CoryWally · Post by **CoryWally** » 25 Jun 2013, 15:42

That's quite a strong statement from Frank which I have no reason to dispute, could be quite different stock either side of the pond. Like I say, my experience from 3 different groups over the last 8 years has been no significant problems with quality and always breeding true. Would be worth seeing how yours turn out and then start making some decisions on improving the quality.

Cheers,
Mark.

rmc · Post by **rmc** » 25 Jun 2013, 15:51

I completely agree. I'm sure the U.S. stock originally came from the UK or Germany, but we may be working with fish that all came from the same group! The breeder I purchased my stock from got his original stock from Frank, so I would think I would see similar results. I spoke with the breeder on the phone last week when I first started getting eggs and he said I will have to cull them. If a high percentage of the fry need to be culled do you think my idea of breeding them back to a standard colored C. schultzei would help?

Thanks!

Rob McLure

Coryologist · Post by **Coryologist** » 25 Jun 2013, 20:44

Greetings. As in all things Corydoras, I generally only report on my first-hand experience that takes place in my tanks, in my fish room. I'm not big on "fish tales." Obviously there are a myriad of determining factors as to what a fish will grow to look like at old age.

My poor experiences with this fish were at a time where 15 to 20 species were spawning monthly and regularly with no incidence of problems outside of the normal Cory raising foibles.

The annoyance I had with the Blacks were poor egg viability, and just a slight difficulty in rearing. Big whup. Life's tough. The significant problem, especially as the fish grew old was spines that were shaped like an "S" and massive cranial deformities. Seeing as how this trait was displayed in young from various combinations of breeders from mixed sources - I just don't feel it was water-quality, food or any one of a dozen things you can name. I'm going with genetics until someone has a better idea. lol

That being said, the fish were popular, I sold many beautiful specimens and everyone was forewarned about the potential problems. No one, cared.

Cheers. - Frank

rmc · Post by **rmc** » 25 Jun 2013, 21:15

Thank you for backing up my thought Frank!

That's what I understood to be the case exactly. I have seen the same S-shaped spinal deformities with (very few of) my Longfin aeneus (another line-bred corydoras). That being said they are otherwise extremely healthy, nice to look at, and productive fish.

Frank do you have an opinion one way or another on introducing some standard C. schultzei genes into the "Black" line? I know you've had more experience with this group (and every other Corydoras LOL!) than I have, so I'm very interested to hear your opinion.

Coryologist · Post by **Coryologist** » 25 Jun 2013, 21:35

rmc wrote:Thank you for backing up my thought Frank! That's what I understood to be the case exactly.

Always my pleasure.

I have seen the same S-shaped spinal deformities with (very few of) my Longfin aeneus (another line-bred corydoras). That being said they are otherwise extremely healthy, nice to look at, and productive fish.

I have never actually seen this in any other species that has spawned for me, that I can recall.

Frank do you have an opinion one way or another on introducing some standard C. schultzei genes into the "Black" line? I know you've had more experience with this group (and every other Corydoras LOL!) than I have, so I'm very interested to hear your opinion.

It would make sense especially as it relates to the one school of thought holding that the strain originated in a spawn of bog-common C. schultzei, was segregated and line-bred from that single specimen in Czechoslovakia. That's the opinion that I'm partial to. There are still many espousing the belief that this fish is being caught in the wild. I'm not sold on that.

Granted, I was no big time importer, but did bring in fish regularly from Oliver at Below Water, Glaser and the normal SA importers when sharing importations with Mark at Anubias Designs. I have never seen or had any one report seeing a true Black Cory, of any stripe, no pun intended. That's over a 10 year span. So, you can see why I'm dubious. That being said, I have a much more open mind than many wish to believe. lol I'm always looking for facts. Bring 'em, on. Cheers. - Frank

CoryfanAad · Post by **CoryfanAad** » 26 Jun 2013, 07:02

Interesting !!! Is this the one that's sold here (Holland) as "Black Venezuela" ??? I also thought there were wild caught ones.

CoryWally · Post by **CoryWally** » 26 Jun 2013, 11:27

Good discussion. On the viability of eggs, again, I've not had a problem so long as I remove the eggs early from the parents, add a drop of methylene blue and aerate vigorously. Extremely high hatch rate.

I've currently got 5 or 6 batches of black aeneus from the last few moths growing out. Not a single throw back to original source, or a single deformity in over 400 fish up to 30mm in size. I had noticed an old female who became a bit gnarly after 4 or 5 years but that's common in older fish. No real problems with adults fish grown on from previous spawnings either.

I believe the black schultzei originated from the Czech Republic or Germany in the 1990's, but Jools will testify to wild black venezuelanus types from his collecting experiences. Could be two totally different sources, which may have been interbred in original development of the one we comonly see from tb stock. I doubt a simple back cross to a 'normal' schultzei will improve the bloodline, only resulting in more throwbacks to original wild form. Unless its a concerted breeding programme over 3 or 4 years. Or just get some of the solid stock from over here and use that to improve bloodlines!

Cheers,
Mark.

dw1305 · Post by **dw1305** » 26 Jun 2013, 14:38

Hi all,
A member of the UKAPS forum unintentionally bred 2 colour forms of C. "aeneus" together, including a black form. Thread and pictures here: <http://www.ukaps.org/forum/threads/do-y ... ost-146238> and <http://www.planetcatfish.com/forum/view ... d&start=20>.

cheers Darrel

rmc · Post by **rmc** » 26 Jun 2013, 15:59

As I understand it the Black C. schultzei strain was developed by Hartmut Eberhardt in Germany. I'm just getting that information by reading internet sources, but the posters are pretty credible. I've seen pictures of the "Black" Corydoras venezuelanus posted in your second link Darrel, but this is not the same fish I'm working with.
Mark I can appreciate that one outcross with a standard C. schultzei won't make a difference for the population as a whole, I'm just trying to improve the stock that I might be able to produce. If I get a large enough population of C.schultzei "Black" going I may try it just to see what happens(assuming I can find some standard C. schultzei! lol) I would love to work with your strain or another group of fish from "across the pond" but I'm just not sure how to go about that. I've shipped plants to London and the guy had them 3 days later - in great shape, but I've been told it doesn't work so well when things are shipped from the UK to the US.

Cheers,

Rob

dw1305 · Post by **dw1305** » 27 Jun 2013, 10:15

Hi all,

As I understand it the Black C. schultzei strain was developed by Hartmut Eberhardt in Germany. I'm just getting that information by reading internet sources, but the posters are pretty credible.

Have a look at:
http://www.planetcatfish.com/forum/view ... +schultzei

cheers Darrel

rmc · Post by **rmc** » 27 Jun 2013, 13:09

Thanks Darrel, yes Coryman and Hans Georg Evers were the sources I was referring to. I have read all this before. The fish I have is C. schultzei(Black) - the line bred form. That's why I originally posted this thread. "Line-bred" forms of other fish "guppies, swordtails, platies, etc." are sometimes crossed with wild fish in the hobby because their gene pool gets "stale" and the offspring of these lines become "genetically weaker" than their pure bred wild counterparts.

C.schultzei(Black), longfin C.aeneus, longfin C.panda, longfin and white forms of C.panda, and to a lesser extent the albino variants of many Corydoras species are the only "line bred" types of corys I know about (Someone can correct me if there are more, or I'm wrong). While one(or a few) fish like this may be seen in the wild as a genetic mutation (example seeing an Albino C. sterbai mixed up with a group of regular sterbai in the wild) it is highly unlikely that one would find an entire group of fish of these lines living together in the wild. I also know that C.schultzei and C.venezuelanus are still considered C.aeneus by science. Just like the L-numbers,C-numbers and CW-numbers in this case "Science" is just too slow when it comes to naming fish. Who know's maybe they'll all still be C.aeneus even after scientific analysis.

rmc · Post by **rmc** » 27 Jun 2013, 14:45

I thought about what I posted earlier and thought of one possible scenario where I might be wrong. If anyone has read the well known studies of the Peppered moth:
http://en.wikipedia.org/wiki/Peppered_moth_evolution
you can see how it might be possible that there are dark colored(C.schultzei"Black") and light colored(Standard C.schultzei) populations occurring simultaneously in different areas (or the same area if the substrate is variable enough). Maybe someday someone will find them and write about it.

dw1305 · Post by **dw1305** » 27 Jun 2013, 16:44

Hi all,
Unfortunately I'm a lot more up to date with the genetics of melanism in Biston betularia (and a few other UK moths with melanistic forms)<http://www.liv.ac.uk/integrative-biolog ... -saccheri/>, than I am with Corydoras. I've recorded moths on our campus since 1993, and supplied material to the Saccheri lab. During that time period both the black "carbonaria" and dark "insularia" forms (different genes involved) of Peppered moth have disappeared from most of S. Britain, reverting to the situation before 1850.

It would be interesting to see what the outcome of crossing them with type C. schultzei, assuming that the black form was originally a mutation in a single fish, rather than artificial selection for dark coloured individuals and line breeding of the progeny. Assuming the black allele is recessive, all the F1 fish would be type, and if it were dominant they would all be black (but some of the dominant phenotype would be heterozygous in either case). If it was originally selective breeding of dark coloured individuals you would get a range of pigment intensity.

Purely in the interest of experimentation, and assuming that type C. schultzei aren't available, I would try crossing a black "C. schultzei" with a type C. aeneus, and then crossing the F1 generation together. Ethically you would then be left with a lot of fish that could only be sold as putative hybrids.

cheers Darrel

rmc · Post by **rmc** » 27 Jun 2013, 16:58

I think standard colored C. schultzei may be available (on this side of the pond at least). Let me send a couple emails out and see if the people I know that kept them still have them or at least know where I could get some. This sounds like a neat experiment!
That being said I would like to get my C.schultzei(Black) breeding as a group first. I looked at their eggs this morning and I have a feeling that this second batch may be as infertile as the first. My group of 7 consists of 4 males and 3 females. They are all young so I may have to be patient. Once I can confirm that my group is a successful breeding group I will try to a.) find some standard C. schultzei b.) cross them with the C.schultzei(black) and c.) share the results! Should make for a good article for my aquarium society's newspaper in the least!

Post by **Coryman** » 29 Jun 2013, 20:00

I was probably the first to have and breed this species in 2003/4 and I never encountered any of the deformity problems mentioned.
For a better result I would take out the largest female and 2 or even 3 of the males and put them in a tank of their own.In my experience 5 males will not cope with 4 females. It needs at least 2 males per female to her stimulated enough to produce at 100%.
I think the idea of adding new C. schultzei blood will pay dividends if done correctly, line breeding is very precise and to get the right results you would need to follow the procedures. I can't explain how it all works as it is something I have never been into.

Ian

rmc · Post by **rmc** » 30 Jun 2013, 18:10

I just cleared some space in my fishroom for a few additional tanks so I will try just that! I think I should be able to put the 2 largest females (they are both about the same size)in separate tanks, each with their own pair of males. I'm hopeful that will result in some viable eggs, as I have yet to see any in 2 spawns so far.

Joost · Post by **Joost** » 06 Jul 2013, 21:02

CoryfanAad wrote:Interesting !!! Is this the one that's sold here (Holland) as "Black Venezuela" ??? I also thought there were wild caught ones.

Yes that is what is sold as Black Venezuela in Holland

CoryfanAad · Post by **CoryfanAad** » 06 Jul 2013, 21:22

Thanks Joost !!!

rmc · Post by **rmc** » 07 Jul 2013, 06:16

@ CoryfanAad and Joost
I ordered 6 Corydoras "Black Venezuela" last week just to compare. The price was good and I can't help it -I'm addicted to Corys! The seller assures me that these are wild caught fish he got them directly from an importer. The pictures he has show a slightly different fish than what I currently have (C.schultzei"Black") It will be very interesting to look at them side by side. When I get them (if everything ships Ok) I hope to post pictures of both fish.

CoryfanAad · Post by **CoryfanAad** » 08 Jul 2013, 09:33

Nice and hey yeah a cory-addiction at this forum? Nothing strange about that hahaha.

Joost · Post by **Joost** » 10 Jul 2013, 18:20

Is it not this one that you ordered?
http://www.ruinemans.com/nl-NL/68826/pa ... zuela.html

rmc · Post by **rmc** » 10 Jul 2013, 19:34

@joost That was what I thought I ordered! I just got them, packing was excellent and all the fish look very healthy, but so far to my eyes they look just like the C.schultzei "Black" fish that I already have! I'll take pictures in the next few days and let other people on the forum see what I'm talking about. In the mean time, I'll try to get information about the importation details of the fish I just received.

Joost · Post by **Joost** » 12 Jul 2013, 20:07

I am still convinced that Schultzei Black is a breeding form. My blacks will also produce some Schultzei sometimes.

Post by **Coryman** » 13 Jul 2013, 17:20

Please do not confuse the C. schultzei "Black" with the one they call "Venezuela Black", this fish is just a darker form of C. venazuelanus and is not actually black. It is also a smaller fish with a completely different body shape.

Ian

rmc · Post by **rmc** » 13 Jul 2013, 17:37

Thank you for the clarification. What I ordered and hoped to receive last week was the dark form of C. venezuelanus, but I think for some reason in the U.S. the label C. venezuelanus "Black" is being given to C. schultzei"Black" on a regular basis(on aquabid.com, and other sites selling corys). The fish I got last week are definitely C. schultzei"Black".

On a positive note, I secured an order yesterday to obtain at least one C.schultzei of standard coloration. It's a start

CoryfanAad · Post by **CoryfanAad** » 13 Jul 2013, 18:36

Ok thanks Ian, so they are different ones. Does that mean Black Schultzei isn't sold in Holland or are they always mixed up and sold as black Venezuela. Can't remember any sold as black Schultzei overhere! I can be wrong. And are Black Venezuela found in the wild instead of Black Schultzei? Greets Aad

donpetty · Post by **donpetty** » 13 Jul 2013, 19:35

To fall into a pile of confusion; this is my opinion;

Corydoras C. Venezuelanus "Black" I do not believe is the same fish as what many here are calling Corydoras sp. Schultzi "Black".
I prefer to not use the moniker "Schultzi" as it references a Corydoras "aeneus" subspecies. My Black Corydoras are solid black with an orange tinge to the fins. I have been selling my offspring as Corydoras sp. "Black";
Line bred creations.(maybe they are all genetically related to aeneus?)
I also have a Black patterned Corydoras which is a darker mid-body patterned Corydoras aeneus (?) with clear to tan fins, which I purchased off of Aquabid as Corydoras "Schultzi", They seem to have a very different body shape and pattern to me. Much closer to what I think is the common "aeneus". I have also seen the same "Schultzi" patterned fish in a fish shop called Corydoras Schultzi-Gold shoulder. Which may be a totally different fish altogether, hence the problem with common fish shop nomenclature. I'm going to continue to call my all black fish <sp. Black>

Don

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