PlanetCatfish.com

I've got some questions regarding my little troupe of C. pygmaeus:

• 1) They are not fully grown; most of them are roughly 2cm (0.8") TL, are they likely to be sexually mature?
  
  2) Are there any known undescribed pygmaeus-lookalikes? I'm asking because I got a lone fish (apparently bycatch with Nannostomus marilynae, a tetra from the Negro), which looks very much like a pygmaeus, but is bigger (3cm TL), is more "free-swimming" than the other (it never forages on the bottom, unlike the others who spend most of their time foraging deep inside my Sagittaria thicket), and has much lighter pigmentation on the dorsal side. Basically it just looks and behaves subtly different.
  
  3) It would be helpful if I could tell if the pygmaeus are spawning. Are there any tell-tale behaviors (e.g chasing) I should be looking out for?

As with most Cory species there is a definite difference in overall size between males and females and with C. pygmaeus males only reach about 20 mm SL (body length), where as females can be considerably larger, growing up to 32 mm SL. This along with the fact that females will generally be plumper in body shape should make it relatively easy to sex them.

Ian

Iknow nothing about the Corydoras cf pygmeus Rio Negro you asked about.

I did have some that came in at what has to be their maximum size. The females were twice the size I'm used to. I set up a spawning tank with the males in it and the female in an ajacent tank and the sides were painted black so they could not seee each other. On the very night before I planned to move the female into the spawning tank she spawned without the males. She laid a surprisingly large number of eggs for such a small Cory but what really amazed me was how large the eggs were.
I never could get them to spawn again.