Actually, mature females look pretty much the same all the time. If there is any difference caused by the eggs, it would be barely noticeable.
However, since corys depend on environmental conditions to trigger spawning, you can help them do it. Feeding live or frozen blackworms, bloodworms or tubifex for a few weeks will help them develop eggs. Then various things, such as water changes, dropping the water temperature, etc. can be done to stimulate them and encourage them to spawn. In nature they spawn when the melting snow from the mountains runs down and cools the rivers they live in, so this is what you are trying to imitate.
If you are thinking about getting them to spawn, which species did you have in mind?
I have a couple of harold shultzi cories and I thought that the larger one was maybe carrying eggs because it's/she's gotten quite large and rotund over the last few days.
If your cory seems OK in every other way, don't worry about it. If she does have eggs and spawns you don't have to do anything unless you want to save them to raise. A first spawn is usually small and will usually be repeated.
I have C. haraldschultzis, but mine are still young, so I cannot tell you anything about their spawning habits from direct experience with them. Most corys are similar though.
On the other hand, you will want to be aware that corys can get dropsy like other fish. Of course, since they don't have scales, they do not get that "pine cone" look about them.
Well i have been into breeding live bearers for a little while and i had to buy a cory to keep in the fry tank to help clean up spme of the mess.....he/she is very good at it too!....How can I sex it? It is a nice sized albino cory
What kind of conditions do they need to breed and what do the eggs look like?
The female C. paleatus in my avatar is pretty mature, and I am currently putting her and a few other through a three week breeding program....
fishguy18, to sex Corydoras, look at the body shape, especially from above. Females are fatter around the middle, and, depending on species, will have rounded ventral fins, opposed to the males' pointed ones. It's easier to have a few Corys to compare when sexing them. Corydoras spawn at the onset of the rainy season in the wild, and need feeding up with bloodworms and other live foods before a cool water change. C. aeneus and C. paleatus are probably the easiest to start with.
Do bear in mind Corydoras are shoaling fish and your single albino (probably C. aeneus) will be much happier with four or five shoalmates.