Females tougher than males?

[Atlantis Child]

Title says it all really. Why I'm asking if you think this may be true is because of my own female to male ratio.

I usually buy my corys in a pair. One female, one male. If tragedy strikes in the tank, it's the male that dies, not the female (yes I'm sure of gender)

Of 2 albinos
Of 2 bronze
Of 2 Juliis
Of 2 skunks
Of 2 metae

This happens over a long period of time, but there's def. a pattern here.

And so I've ended up with 11 female and 1 male. I suppose some of it could be chance, but given that, if more males than females are sold at the fish stores. That may be true if they are actually tougher.

I've found this with whiteclouds and zebra danios as well. Noticed the same sort of thing whilst working at the fish room at my local petstore too.

What do you think? I'm rather curious if this happens outside my cat tank.

I actually did purposely buy 2 male paleatus cats to join my 2 girls. They make a cute little group, and while not the prettiest, I find them very social, hardy, and the least shy.

So now it's 11 female, to 3 male. Sheesh.


- Atlantis

[andywoolloo]

I keep cories three to one, three males to one female. I'd have to say in my opinion they are a hardy fish regardless of sex. I haven't lost any in the 15 months I have had them so far. Knock on wood. So unknown about your theory. It's interesting tho.

[Bas Pels]

Just thinking aloud

in Corydoras, females are larger than males, and yes, large fishes are most often hardier

So this could be a line of explanation, perhaps

(in cichlids males are often larger, and many people are left with only males, but here intraspecific agression simply kills more females then males, as this agression favours the larger fish. another mechanism, thus)

[Richard B]

Just thinking aloud

in Corydoras, females are larger than males, and yes, large fishes are most often hardier

So this could be a line of explanation, perhaps

(in c*****ds males are often larger, and many people are left with only males, but here intraspecific agression simply kills more females then males, as this agression favours the larger fish. another mechanism, thus)

Bas Pels is right about bigger fish being hardier but would this apply to the subtle* difference in sexes of corys?

*compared to the difference between (for example) a cory & an oscar.

[Yroc]

My experiences during years:

- 2 large females aeneus, both died after 8,5 and 9 years of age
- 1 male aeneus albino (normal size), still living after 16 years

Now there are several Cory's in my tank, beside that old male:

- A group of 4 sterbai, of wich ther are 2 very large female of about 3,5 years old
- A group of 8 aeneus, with one large female (2 years, 3 months) (a young of the old albino and of one of the large females)
- One paleatus, I think a man, with a high fin, of about 3 years

The last year I lost to small C. aeneus (had 10).

So I think they can grow old, and largeness seems to be an issue.

[apistomaster]

When it comes to Corydoras spp, I know of no difference in the life span between the sexes.
I personally know of some Corydoras which have lived over 10 years in captivity.
I don't believe there is any built-in difference between the lifespan of the sexes in genus Corydoras.
Using inductive reasoning and applying that to what is actually a scientific question is dangerous. Logic can dismantle any conclusions you draw.

Any differences you have noticed constitute too small a number to be statistically significant. You are only seeing a coincidence.

You must also take into account the factor that in wild collected specimens, the best you can do is estimate the age of the fish.
You must have fish of a known age and many of them for their entire life to draw any meaningful conclusions.
If you have Corydoras dying before their time, what you should be concerned about is what is killing them and address the cause.

[Atlantis Child]

"I personally know of some Corydoras which have lived over 10 years in captivity."

Awesome!


"Any differences you have noticed constitute too small a number to be statistically significant. You are only seeing a coincidence."

Yeah, probably. I did want to see if there was anything similar from cory keepers here though anyways.

I wish I could do a survey from a large group of catfish, also noting suspectability of disease. (not by introduction, just over the natural course of time) I'm no biologist, but a home experiment would be interesting. Unfortunately that's not possible right now as I don't have the time, space or ability to get catfish all from the same clutch.

Hopefully someday.


"If you have Corydoras dying before their time, what you should be concerned about is what is killing them and address the cause."

It was during a big problem of high pH. That was fixed, and equilibrium seems to be back. All's good these days, and I'm keeping a better eye on things.


- Atlantis

[Atlantis Child]

Oh, and the corys were almost adult size, but not quite. But the pairs were still equally sized (except the slight belly of the girls)


- Atlantis