Breeding behaviour in pygmy corys

[iramjohn]

I am trying to convince my pygmy corys to breed (my father-in-law suggested Al Green music, but it didn't help much), and after a water change on Saturday night and a good storm system last night, they seem to be thinking about it, though I may be wrong. The tank is densely planted, so I rarely see them.

Anyway, today one female and two males were out in the open. I have seen what I believe to be mating-type behaviour in my other corys, in which the male pursues the female around the tank. From what I have read (about C. aeneus) there is no female choice, instead she tends to mate with whichever male is most persistent. This was different - two males sat above the female, rapidly beating their pectoral finds and the top of their caudal fin. The female sat of a leaf just below them, and joined them a couple times doing the same rapid fin-beating. Does anyone have any idea - is this "courting" behaviour? Do pygmy corys exhibit female choice? Or is this just a nice afternoon stroll?


Temp: ~73F, pH between 7 and 7.5, GH ~60 mg/L, KH ~40 mg/L, nitrates/nitrites ~0 (it's a heavily planted tank). Tankmates are Otocinclus and Cherry red shrimp.

[iramjohn]

I've got more of the same behaviour today, only instead of two males around a female, there are either three males and two females, or four males and one female (it's hard to tell - overall the sexual dimorphism is pretty clear - big, broad females and small slim males, but there's one fish that's intermediate in size between the males and the females, and appears to be slightly stockier in build).

I'm pretty sure this is breeding behaviour. Am I reading this right? Does anyone know if C. pygmaeus exercises some amount of female choice? Or are they just impatiently waiting for her to get "in the mood"?

[apistomaster]

I breed Dwarf Corydoras in a natural set up. A permanent planted tank with less than 1/4 inch of fine sand. Some potted plants and a lot of floating Hornwort. I may have red cherry shrimp sharing the breeding tank because I have seen no difference in my final numbers of surviving fry and they contribute to keeping the breeding tank clean.. I feed them daily with live black worms and live bbs. Cultured Grindal worms are an ideal sized conditioning food if you can raise them.
I keep them in about a two males/female ratio and find that larger groups are easier to breed than just one trio. I usually start off with a dozen breeders. Over a few months you should be seeing glimpses of larvae near the bottom and as they mature and begin to look like the adults,they will join the main school. After a few months, you should have several dozen and growing number of fry. With C. hastatus, I began with 12 and four months later, I have about sixty and still increasing.
They typically go into a spawning frenzy shortly after a large water change of water cool enough to temporarily drop the tank temperature by 4 or 5*F.
I find it much more difficult to breed just a trio. I use a 20 Long as the spawning/rearing tank. Be sure to use sponge filters or sponge prefilters on any HOB filter intake tubes. Your fish seem interested in spawning but not quite worked up enough to breed yet. Live bbs each day will greatly increase their desire to breed along with large cool water changes. Many males contribute to competition to mate. Females do choose the males they mate with. Males have no ability to force a female to spawn but the competition of many males promotes her willingness to spawn.
This method works well with C. hastatus, C. habrosus and C. pygmeus.