I have noticed that my L numbers and some of my corys have been reluctant to breed. I first thought it was them being lazy but after much thought and some research I found out that it was me. When my corys and L numbers were spawning great I was changing a lot more water in their tanks. Over the last couple of years that slowed down to only once a week. That resulted in a saving on the water bill but little or no spawnings. So I did some research as to why my L-46 Zebras had only spawned a few fry twice and missed last spring completely. My search came up with this article http://www.zebraplec...opic.php?p=4635 I followed Barbie's recommendations and gave the zebra tank a 1 third water change with cool RO water every evening for a week. After only the third change a male caved up and a female joined him on the fourth. I continued to do the water changes for another week but as the TDS had dropped below 50 I premixed pails of RO water to read about 50. This morning was my reward as I can see a few fry wiggling above the male in his cave. I hope I can keep him spawning for the winter.
My Corydoras weitzmani have not spawned in 3 or 4 years. Again at the OCA Convention Ian Fuller suggested multiple water changed to trigger corys to spawn. Come to think about it that is what I did years ago when I first got them. A week of cool water changes some with RO and some with cold tap water. After a few changes daily I got 5 eggs. A couple of days later 17 and today 32. Remember it is not the fish that get lazy it's you.
This should work for just about all L numbers and cory cats. Keep them in hard tap water at the top end of their temperature range for 6 weeks. Then lower the temperature a few degrees and the give daily 1 third Ro water changed for a week. I would not let the TDS go much below 50 Although some rivers can be as low as 10