Re: GUPPIES GESTATIONAL PERIOD AND BREEDING HABITS

I can certainly identify with your fish breeding troubles. I must admit I have never tried to breed guppies before, but the zebrafish that I work with in my laboratory have given me plenty of breeding problems in the past.

First, there's technically no such thing as a "pregnant" fish. When fish breed, fertilization occurs externally - that is, the female and male get real close together and both release their gametes into the water at the same time. The eggs and sperm meet in the water, and the fertilized eggs then fall to the floor. The guppies with the full bellies are probably females that are carrying around eggs waiting for the "right guy" (we would say these females are "gravid"). This also means that your fish are relatively happy and healthy, since unhappy fish don't become gravid. So here are a few tips on how to get your fish into the mood to breed:

1. You will need some way to separate the fish from their eggs the second they are fertilized. Fertilized eggs are the fishes' favorite snack - even if it's their own eggs! We usually separate the fish from the bottom of the tank with a screen, so the fertilized eggs can fall through the screen and land safely on the floor.

2. Put a couple of males (they're the skinny ones), and several females in a confined area to breed. If they're relatively close together, they tend to be more "in the mood".

3. If they do breed, move the eggs to another container for the duration of their lives, since older fish will eat them. Inevitably, some of the eggs will not be fertilized and will die and rot, potentially causing other healthy eggs to die. Remove molding dead eggs as time passes.

Sometimes all these things can happen in a tank environment, but these are some ways to increse your chances. Keep in mind that young fish embryos are very small - there may be some in your tank which you simply cannot see yet. Be patient and give these things a try. Good luck!