If you've been having problems with the common type livebearers, you are not alone. I myself went through this the past year or so. Keeping many "hard to keep" fish species, and yet I couldn't keep mollies, platies, swordtails, and guppies alive?!
Through many hours of research and other hobbyist help, I found the cause to be how they are commercially raised. The cement ponds that are used to breed livebearers in leach into the water raising the pH and hardness. Unfortunately for me I have very soft water, this was stressing my newly acquired livebearers to no end. No matter how much attention I payed them I couldn't get them to live. Simply dismissing it as too "inbred". While many livebearers have been downbred, my luck did a 180 as soon as I raised the hardness of the water in the livebearer tanks.
For a more in depth read and pictures, you can check out the article on my blog: http://www.tankgeek.com/2011/02/11/livebearers-weaker
Through many hours of research and other hobbyist help, I found the cause to be how they are commercially raised. The cement ponds that are used to breed livebearers in leach into the water raising the pH and hardness. Unfortunately for me I have very soft water, this was stressing my newly acquired livebearers to no end. No matter how much attention I payed them I couldn't get them to live. Simply dismissing it as too "inbred". While many livebearers have been downbred, my luck did a 180 as soon as I raised the hardness of the water in the livebearer tanks.
For a more in depth read and pictures, you can check out the article on my blog: http://www.tankgeek.com/2011/02/11/livebearers-weaker