Why do my guppies keep dying?

Dying can be caused by a few different things. Young guppies that are impregnated early (before they are close to full grown) often die due to the stress of birth. Guppy males will start trying to mate the female fry (young fish) as early as about 4 weeks of age. The second reason is also due to stress, but stress caused by males in the tank, constantly chasing/trying to mate with the females. It's recommended to have at least 3 females per 1 male in a tank as a distraction, allowing the female to get some much needed rest. It's also a good idea to separate the female after birth for a few days from the males in the tank, so that they can recover from birth.

Also, female guppies get exhausted easily from having fry, if you have males in the tank with them right after having fry it doesn't give them a chance to recover. They need quiet and brine shrimp for iron after having fry, some people put a small amount of Epsom salts in the tank also this seems to help. A teaspoon to ten gallons of water is right, or a pinch to a gallon of water.

Also, water parameters may be off with ammonia or nitrite too high. The babies will be more sensitive.