PlanetCatfish.com

Hello everyone! If someone can help me, I would sure appreciate it.

At first glance, some of you may think that I'm "breaking the golden rule", and asking you how I can distinguish the difference between my male and female fish. No sir! That is not the case, so please don't throw tomatoes or rotten eggs at me. That is not what I am asking.

Here is my situation. I have never owned Corydoras Pygmaeus before. I recently purchased 24 of them, from a seller who said that they were wild-collected, and that he had kept them in quarantine for AT LEAST 60 days. He assured me that they would be very healthy specimens.

I must say that I was quite pleased when they arrived. There were no D.O.A.'s, all of them appeared to be very frisky, had good color, good fins, swam around and explored their new home, and had no visible imperfections of any kind. When I began to feed them the next day, they ate. I've worked hard to treat them well, BUT I ADMIT THAT I AM NO EXPERT ON THESE FISH. So in addition to the question(s) that I'll ask, please feel free to tell me, if you think I could do something better than I'm doing.

These Pygmaeus are presently in a 10-gallon tank, with no substrate. (I plan to use fine substrate in their breeding tank some day, but I was hoping to avoid it at this time.) There is a large sponge filter, an airstone, (2) coconut caves with Java Moss, and driftwood in their tank. I feed them frozen B.B.S., decapped brine shrimp eggs, New Life Spectrum (ground fine), Banana Worms, Walter Worms, and Micro Worms. As far as I can tell, they are very healthy, and doing well.

Now --- to the crux of the matter. My goal has been to "raise them up", make them healthy, get them to the point of sexual maturity, and then pursue a breeding program with them. In order to do that, I've realized that at some point I would need to know that they are sexually mature, and I'd need to be able to determine which are males and which are females. Once I can do that, I would like to move a group of them to a breeding tank, and then go from there.

I believe I have seen them become slightly larger during the 6 weeks that I've had them, but that is difficult to determine, because these are small critters! So here is my main question, (plus a bonus question or two):

--How can I know if these fish are sexually mature?

This is how I've tried to think it through: With regard to their age, I assume that they were born in the river, and at some point, they were caught and sold to someone. At some point, they ended up in the hands of the person from whom I purchased them. Assuming that he is correct and truthful, he had them for at least two months. Based upon what I've seen, I have no reason to doubt him. Now I've had them for 6 weeks. I could add all of that up, but I don't know how old they were when they were taken from the river, so that doesn't help much.

--With regard to trying to determine sexual maturity from appearances, I can tell you this: If I look at them closely, I can see that there is a distinct size difference between the largest ones, and the smallest ones. The largest ones are *perhaps* 3 mm bigger than the smallest. And if it's not my imagination, I believe that the largest ones are, in fact, more "robust" or plump, than the smallest ones. So -- is it reasonably safe for me to assume that the biggest ones are females, and the smallest ones are the males, at this point?

And if that is the case, then does the fact that I can now determine males from females, NECESSARILY mean that they are sexually mature at this point?

REMEMBER PLEASE that I don't want to be guilty of asking how to determine the boys from the girls. I don't want to be banned from this site. So I've done my studying, and I am familiar with the methods that are used to distinguish cory males from cory females. With my other cory varieties, I am able to determine the difference between the males and the females. But with these Pygmaeus, I cannot see any difference in the ventral fins, the dorsal fins, or any other fins. I cannot see any differences ANYWHERE on their bodies, except for the size difference that I mentioned above.

If anyone feels the need to provide suggestions/corrections regarding the other parts of my approach, please do so. I am in this to learn, so constructive criticism is always welcome. Thank you, everyone, and have a great day.

I'm tempted to just answer - yes, yes, yes, yes and yes!
but I shall refrain.....

You've researched well. And after 6 weeks with you, they are clearly settled in and thriving.
The main sexual difference with this fish is the females appear so much more robust. Bigger in all respects. Follow the usual advice for keeping corys, with plenty of live/ frozen live food and cool water changes..... and they will show signs of mating behaviour.

You're a bit nervy of asking questions....? Even the most experienced fish keepers can learn from others' experience.

Hello "wrasse"!

Thank you, so much, for your input and advice. I appreciate it.

Ummm... you brought up a good point:

You're a bit nervy of asking questions....? Even the most experienced fish keepers can learn from others' experience.

This is why I am "nervy", and after I tell you, perhaps you'd be willing to provide your perspective on what I have to say.

I am very NEW to this site/forum, and I LOVE it and am grateful for it. Being able to discuss this hobby with aquarists from around the world is like some kind of dream-come-true for me. But as I looked over this site my first couple of times, I saw many warnings, telling users to read this or that, PRIOR to asking questions, so they don't keep asking the same questions. I saw someone creating a "post it" - (whatever that is) - that instructed users/readers regarding how to tell their boy corys from their girl corys, "because this question comes up so often". And I also saw some forum rules, begging new users to read all the F.A.Q. and to search the forums for answers first, so those new users would not keep asking the same questions. I got the distinct impression that asking certain questions that have been asked before, is a BIG no-no. I am someone who likes to follow the rules, and I don't want to be a troublemaker!

So -- although I LOVE to discuss this hobby with other aquarists, and I enjoy asking a lot of questions so I can learn, by the time I got up the nerve to post my question on this forum, I was concerned that I would accidentally ask one of those commonly-asked questions, which would result in someone getting irritated, and then, before I was a member of this site for even one month, someone would either censor me, or ban me from the site. (I'm exaggerating a little bit, for entertainment sake, but ONLY a little bit.) So that's why I'm so timid about asking questions.

Perhaps I'm over-reacting, or I got the wrong impression. I would be happy to hear any comments you might have about this.

And again... thank you wrasse, for your response. I am most excited to see if I can get these little guys to spawn.

Hey, I don't think you are over-reacting. I'm not surprised at all.

I suppose its our passion for the hobby. But your view counts as much as anyone's. You did your reading-up and it seems to me you know your corydoras.

Sometimes, peoples' replies seem to 'jump out' at you. Sometimes its with humour, and sometimes its overly serious.

Btw - WELCOME TO PLANET CATFISH

wrasse wrote:The main sexual difference with this fish is the females appear so much more robust. Bigger in all respects.

This is true- I'd say maturing females are easier to spot in pygmaeus than in larger corys, because they're probably nearly twice as heavy as males.

Hi guys. Thanks again, for your input.

I don't know if I'm about to break another "rule". Is it okay to respond to two different people, in one reply? That's what I'm about to do, but I'm feeling a little sheepish.

Wrasse: You helped me to relax a bit, and enjoy the forum. And thank you for the welcome. I appreciate it.

Carp37: If my "females" are only a LITTLE BIT bigger than my "males", then is it probably safe to assume that they are still in the process of "maturing", and that over time, I'll observe an increase in the difference between the males and females?

Thanks. Have a great day.

Aquafinatic wrote: Carp37: If my "females" are only a LITTLE BIT bigger than my "males", then is it probably safe to assume that they are still in the process of "maturing", and that over time, I'll observe an increase in the difference between the males and females?

Hi Aquafinatic- I've only got mine to go on- they all started out about 1/2" SL, and over time (probably about 6 months), the males reached about 1" SL, the females probably 1.25" SL, but much deeper, and, as Wrasse stated, more robust all round. Mine never bred, despite looking interested a few times, whereas a colleague of mine has his breed regularly, but I'd guesstimate that they should be mature in a year or less.

Despite being tiny, they're not necessarily short-lived- I'm sure I've seen a forum post on here where Ian Fuller stated he'd had a female 17 years. However, they are delicate compared with some species- people on this forum have had differing levels of success with them. 10 of my 12 survived the first year, but I've since lost another six in the next 18 months, so I'm not the best expert on keeping them alive!

Hey Carp 37,

Thanks. You must be reading my mind.

Even though I generally have good husbandry skills, I tend to expect a few deaths, especially when I buy a fairly large group of fish. In the case of these C. Pygmaeus, I purchased 24, and that's the most I've ever purchased of any species, at one time.

On top of that, I purchased WILD-caught ones, and many people suggested that I could expect a higher mortality rate. I will admit that I've been surprised, as none of them have died. Perhaps I'm on my way to having a "first year" that's similar to yours. But I have been wondering, (such as when I was a bit late on my water change, or when I accidentally got some of the oatmeal/yeast into their tank, along WITH the Walter worms), when I was going to come home from work, and find some casualities. This is certainly a learning experience.

One more point: I wonder if yours were tank-raised, or wild? Do you have any strong beliefs regarding the discussion "out there", that the wild-caught cats are more difficult to breed, than the tank-raised ones?