Q. I am having problems keeping my newborn livebearer babies alive. They live for a few days, sometimes longer, then they start dying. I keep them in a 4-gallon aquarium with an undergravel filter. These are mostly fancy guppies, platies, mollies and so on (salt was added to the water for the mollies). Can you help me?

A. I doubt that a water quality problem is the cause of the deaths. Young fish tend to die immediately from serious environmental problems or in four to five weeks if there are heavy metal toxicity problems. Fry that die in four to seven days usually succumb to starvation.

You didn't mention what you are feeding the baby fish. Try hatching some live brine shrimp nauplii and feeding them to your young fry. The movement of the nauplii attracts the fry and stimulates a feeding response. This may help with your problem.