How to Control Guppy Population – Overpopulation of guppies and their fry is one of the common problems that aquarists may have experienced at one time or another. Knowing how to ‘nip the problem in the bud’ will help eliminate and/or control the problem. Here are common methods that are used to address the problem.
1. Adding larger predator fish to the tank
Removing aquatic plants from your will expose a whole population of fry hiding from predators. Larger predator fish would make short work of your guppies, thus you will have to provide other food sources.
Some of the popular fish species that prey on guppy fry include the following:
- Paradise fish
- Siamese fighting fish or betta
- Tiger barbs
- Zebra fish
- Angel fishes
- large Catfish
- Bluegill sunfish
2. Separate males and females
In order to effectively separate male and female guppies, you need to know how to distinguish between the two, or else you might have one or two that may escape your notice and you will still have some “fry-producing machines” in your tank.
Use separate tanks to separate the sexes. However, if you have no extra tanks, and your tank is large enough, you can put in a divider between the male and female guppies.
How to distinguish male and female guppies:
You may need to take each fry out of the tank individually and place it in a clear container. Use a magnifying glass to determine if the fish has a gravid spot; if it does, place it in the female tank.
- Female guppies are much larger than males
- Females have dull colored bodies with brighter colors enhancing the tail
- Male guppies have brilliant colors, and there are endless possibilities of patterns and colors
- Male guppies have longer tails and tail fins compared to female guppies.
Keep in mind that the gender of guppy fry develop when they reach their four-week mark, and they become sexually active at the six-week mark, so it is important to separate the males from the females between these two periods to prevent breeding.
3. Get an “overflow” tank for the excess
Using another tank for the “overflow” is usually a temporary solution, because your guppies will still continue to breed and multiply, and eventually the “overflow” tank will be filled up too.
4. Sell, give, or trade
Ask pet shops in your area if they will purchase fry or are willing to exchange the fry for store credit.
If you are a member of a local fish enthusiast club, members may want some of your guppies.
Especially locally owned ones, chain stores won’t bother.
You can also go online and advertise guppies in Craigslist, for free or for a small fee.
This is often the last alternative if all the other control measures prove to be inadequate. Some hobbyists may be strongly against this method of controlling guppy population where the best of the guppies are chosen and the rest are euthanized.