As I've matured as a livebearer hobbyists, I've come to realize that most livebearers will eat their fry if given a chance. To get the best production from your fish, you will need to find a way to save the fry. Some hobbyists use heavily planted tanks, but that makes harvesting the fry a pain. I've successfully used plastic mesh fry traps (see Build your Own Plastic Mesh Fry Trap), but larger species and even some smaller species get very stressed in a small trap.

Not long ago, I saw a Russian-language publication which included a photo of a glass fry trap. While I couldn't understand the text, the pictures were enough to allow me to recreate the trap inside a standard ten gallon tank. Below is a picture of the completed trap, diagrams and building instructions. Enjoy!

Completed Brood Tank: How it Works

A Swiss Tropicals Jet Lifter tube is used to provide gentle current in the main (brooding) area on the right side of the tank. When the female drops her fry, the current pushes the babies through a 3/16-inch gap into the compartment on the left side of the tank. Water continuously circulates from the brood side to the fry side, passing through a Poret foam filter. You get great filtration in this set-up.

Glass Breeding Trap


Building the Trap: Materials List

The sizes are approximate for building this in a standard ten gallon tank. Measure the width of your tank and subtract one-eight inch. It should be close to the dimensions below.

You can have your local hardware store or glass store cut the glass. Some might also drill it for you, but you can easily drill the glass yourself. Look on eBay or Amazon for 1.5 inch Glass Drill Bits. Don't be afraid to drill glass . . . it actually is very easy to do!

Obligatory Warning

Glass is sharp! Be careful when handling it.

Plan Layout

Here are some drawings of the various components of the tank:


  1. Drill the 1.5-inch hole in the glass if the hardware store did not do this for you
  2. Cut the Poret Foam angled piece. It is easy to cut with a standard kitchen knife
  3. Place the Poret foam on the left side of the tank. The higher side should face to the right.
  4. Cut a 3-inch piece of masking tape and attach it to large piece of glass (the end with the hole)
  5. Align the tape side about 3-inches down from the top of the right side of the tank. The left side should rest on the left side of the Poret foam block.
  6. Grab a piece of wood or a stack of playing cards 3/16-inch thick. Tape it to the left (lower) side of the angled glass. You will use this to set the gap for the trap.
  7. Test fit the vertical glass. Align it directly on top of the left edge of the angled glass. If it is too tall or too short, you can adjust the angle of the main glass or cut the Poret foam so that it isn't as tall. Once you have it right, use masking tape to secure the vertical glass to the tank. Just a few pieces to keep it in position.
  8. Grab the Silicon Cement and run a bead to secure the angled and vertical glass pieces in place. Let dry for four hours.
  9. Remove the masking tape and use the Silicon Cement to fill in any gaps.Let dry for 24 hours.
  10. Pull out the Poret Foam angled block. I looped three nylon cable ties though the foam. These act as handles and makes it easier to remove.
  11. Cut a hole in the 2" by 2" by 3/4" Poret Foam block about 1/4" smaller than the diameter of the JetLifter.
  12. Add an airline to the JetLifter.
  13. Push the Jet Lefter and airline through the foam block
  14. Wedge the JetLifter in the 1-1/2 inch hole in the angled glass
  15. Fill the tank with water, connect to an air pump and let the tank cycle.

Final Tips

It is helpful to have a control valve on your air flow. You'll want the flow higher prior to birth and then lower it aftewards.I raise the fry in the trap for ten days to two weeks before gently netting them out and moving them to a rearing tank. It is helpful to add some floating plants for the female to reduce her stress.

If I could,I would figure out a way to make the gap adjustable. Three-sixteenths is good for most poecilids, but it might not be big enough for some larger goodeids.