By James Cawein Jr AKA redoscar12
Heres how I do it. Its safe for the parents and fry.
To successfully breed guppies you will need a minimum of 10-gallons but a 20 or bigger(recommended) hood with light, gravel, plants. small filter, divider and 3-way breeding trap for beginners.
FIRST: Put the divider so the tank is on one side 75% and 25% or 50/50. Small side for babies and big side for adults. SMALL holes only in the divider so the fry can't get over to the other side.
SECOND: Place gravel in and heavily plant the fry side.
THIRD: Set the filter in the adult side. Also a sponge filter is recommended in the fry side of the tank.
FOURTH: Add water
FIFTH: Ensure the tank is properly cycled.
SIXTH: Add fish, I suggest four females and six males. And a Cory catfish to catch the extra food. (*Adult side only*)
How to breed: To tell if the females are going to pop (Give birth) look at the back of them. There should be two vents. One on both sides of the anus. Once they turn black keep a close eye on them. When they turn pink its time to put them in the breeding trap. Once she is done place the fry in there side of the tank (25%). Feed the new fry newly hatched brine shrimp, plankton, daphnia, and crushed flakes (my suggestion). Good luck!
Here's Salukis suggestion.
Set-up A small pump or powerhead-driven sponge filter for each tank - This provides more than enough bio and mechanical filtration, and prevents fry from being sucked into the filter.
An inch or so of medium (about pea-sized) gravel in each tank - This allows hiding places for the smaller fry.
A bunch of Java Moss in each tank - This provides cover for larger fry. Aside from the excellent cover it provides, the great thing about Java Moss is that it will grow anywhere, regardless of lighting or nutrients. It is the only truly fool-proof plant I have ever found.
Place 1 adult male and 4 or 5 adult females in one tank. As a female nears term, remove her to the grow-out tank. As soon as possible after she gives birth, put her back in with the adults. This minimizes the number of fry she can eat. Once you get it going, each female should produce a new batch of fry about every 1 to 2 months. Before you know it, you will have more fry than you know what to do with.
If your fish will ever be sold to a store, or be given to other fishkeepers, you need to be concerned about genetics. To insure genetic fitness, you will need (at a minimum) to cull out any fry that show defects. Also, occasionally replace your breeding stock with new fish to introduce genetic diversity. Never breed siblings when genetic fitness is a concern.