what have you found to cause cory's to lay eggs

[resser]

I have 4 cory's in a 55 gal com. tank. some times when I do a water change the next day the corys are starting the egg laying process. (Always when I am at work) so of course I have only been able to save a couple of eggs, actualy about 40 total out of 1000.

The situation for the eggs never seems to be the same, to I don't know what the "trigger' is for the cats so I can replocate it under controlled situations.

Does anyone have any suggestions?


Thanks

[shev]

putting ice cubes in the filter, or doing a water change will simulate rain or something that triggers corydoras to spawn. usually in the morning after adding the ice cubes or doing a water change they will spawn. they are from the amazon and its tributaries, they congregate in small pools, then it rains and they spawn.

[Fishnut2]

Hi Resser,
4 cories won't lay 1,000 eggs, but the best thing to do, is move the spawning colony to a breeding tank. A 10 gallon will be fine. (under $10). Keep it bare bottom with just a filter. Once the fish spawn, you can pull the parents. and put them in another tank (back in the 55 if you have to). Conditioning/cold water change/and good aeration are the triggers! A breeding tank is the best solution to your problem

[DavidDoyle]

Putting icecubes into a filter with bio media is a good way to kill off a bunch of the bacteria you worked so hard to colonize.

[Larry-T]

The easist way to get seasonal Amazon basin breeders to spawn is simiple:

Put them in the proper tank.

Condition them well.

Do a 25-50% water change with water that is both cooler (10 degrees or so) and softer than the existing tank water.

Spawning usually takes place within 24 hours.


What you are doing is simulating the onset of the rainy season, which creates an infusoria bloom as the rivers rise and flood more of the land. So when the eggs hatch, there will be sufficient food to ensure the fry a chance to grow up.

[Thunderkiss]

For best results, wait til you actually WILL have rain before doing the water change. 50%, 10 degrees cooler ish than normal tank temp and MUCH softer (rainwater, R/O or distilled). The change is barometric pressure will add more realism to your artificial rainstorm you are simulating.

[garfieldnfish]

Now let me get this straight. Here you all advise to add water 10 degrees colder to initiate mating behavior. And I got walked all over once in a different forum because I use tap water (water purification system) and adjust the temps by holding my hand under the running water until it feels "about right". I was told this is a good way to kill the fish if the temps are off by more then 2 degrees. Is this not also one of the reasons we place the bag with the fish in the tank rather then just tossing the fish in. Or am I missing something here?

[Fishnut2]

Hi Garfieldfish,
You wouldn't want to do a 10 degree drop with livebearers, or most cichlids. But it works great as a trigger for cories. I combine the softer water, and colder water ideas...but using RO ice cubes. I put them right in the tank, not the filter. A typical drop in temp for my cories is 72 to 62. A few species are more sensitive then others. Don't go under 55. They'll start to do somersaults...or just lay on thier sides. Don't worry if this happens! Just warm them up, and they'll be fine. Small temperature changes are common in the wild. From shade to sunlight/surface to deeper water/ Rain/flowage from another source! Try it on your cories...They love it

[garfieldnfish]

My corys are in with otos and glolights. My glolights have spawned before as did either the corys or the otos. In the glolights case, I was able to watch the spawning and caught a few eggs with a brine shrimp net, but not knowing any better I put them in a glass jar and warmed the water by shining a desk lamp on them, effectively killing them off. With the other eggs they were attached to some hornwort and I believe they may have been oto or cory eggs but they fungused. I was told that corys usually do not use leaves but the tank wall to deposit their eggs, so it may well have been my otos, too bad they did not make it. And this happened each time after a large water change and feeding grindal worms for 2 days straight. But I did not change the water temps at all. (Well, at least not by more then a little using my hand under the running water method).
But I am reluctant to change the temps by that much fearing the otos and glolights would not make it through that.
My skirt tetras spawned for the second time. They always do this in the morning when I am usually at work but I was off last Tuesday and got a few of the eggs. I hatched them in a breeder net and ended up with 2 fry. Today they did it again (water change last night) and I got a bunch more eggs. I used methelene blue to keep them for getting fungus and I hope a few more will hatch this time. I put the eggs in a 2.5 gal plant tank but there are some snails in it, so they might get a few of the eggs before they get a chance to hatch. But since I really don't want any more skirts, that's ok with me. I am just practising for when my zebra plecos get in the mood, which won't be for at least 6 months, but by then I want to be ready.

[Fishnut2]

I have single species tanks, for the sole purpose of breeding. The tetras and otos you have in the same tank, won't do well with a 10 degree drop. Most cories prefer to spawn on glass, but some will spawn anywhere. I've had aeneus and napoensis, spawn on the glass/heater tube/thermometer/airline/plants/filter and literally anything else in the tank.