How do I get my Corys breeding?
I have been attempting to breed my
Corydoras pygmaeus for around six weeks. I have five left after my group of 10 was reduced by a bacterial infection, and I wish to bring their numbers back up the ‘natural’ way.
I definitely have a mix of male and female. However, my observations as to how many of each swings back and forth depending on how much live food I’ve been giving them!
They are currently in a 25 l/5.5 gal tank with a sponge filter, two ornaments for hiding, and a thin layer of sand. My method is to do daily 50% water changes, topping the tank back up with a mix of 50% RO water and 50% tapwater (which has a ph of around 7.5). But I’m getting no breeding behaviour at all and can only find conflicting opinions and advice online and at my local fish shop. What is your take on this?
Also, should my Corys breed, will pond snails, Malaysian trumpet snails or Ramshorn snails eat the eggs? ANDY, EMAIL
BOB MEHEN says: Pygmy corys are lovely little fish. Due to their small size and popularity they make a great breeding project and it’s easy to find new homes for any extra youngsters. It sounds as though most of what you have done so far is a step in the right direction, and with a few small changes you may have more success.
What is the ph of the water in your tank? The ph of 7.5 you mention is probably a little high, especially if you’re in a hard water area. Ideally you want soft, slightly acidic water with a ph of around 6.5. This might not sound like a big difference but the ph scale is logarithmic, so ph 6.5 is 10 times more acidic than ph 7.5. Like many Corydoras, it seems that
C. pygmaeus spawns after rainfall in the wild, so dropping the temperature of the water you use for your water change by a few degrees from that in the tank, and increasing circulation (perhaps adding an extra airstone) may help simulate this and trigger spawning. You also need to make sure you condition the fish well beforehand with a good selection of appropriately sized foods. Frozen foods like Daphnia and Cyclops help in my experience. Having more males than females is good too, as the extra competition stimulates them further.
Most Corydoras will eat their own eggs so it’s best to remove the parents after spawning – this will also make it easier for you to provide the best conditions for the fry to thrive, as well as remove competition for food.
I wouldn’t trust snails with the eggs either, so make sure there are none in the breeding tank.
Cool acidic water is whats needed for cory breeding.