By Ted Judy
• 1-inch diameter rigid plastic tube (standard lift tubing), a 2-inch piece, and a 6- to 8-inch piece
• 2 bull’s-eye pieces from sponge filter frames
• 2 pieces of fish net, cut to 2-inch squares
• 2 submersible heater suction cups with brackets (large enough to hold 1-inch diameter tube)
• Airline and a source of air
Building and Using the Tumbler:
1) Place a piece of net over one side of a bull’s-eye and push the longer piece of plastic tubing over it so it is held tightly in place.
2) Slip the heater suction cup brackets around the tubing, and then sink the not-quite-finished tumbler into the aquarium you want the eggs to be incubated in. Secure the tumbler to the glass of the tank with the suction cups (with the open end up) and push it down until the entire tube is under water.
3) Place the eggs into the tumbler through the open top. They will fall to the bottom and rest on the netting.
4) Hold the second piece of net over one side of the second bull’s-eye and carefully insert it (net side down) into the top of the plastic tube.
5) Slip the airline from the air source through the smaller piece of plastic tube. Attach the airline to the center port in the top bull’s-eye, and then push the plastic tube onto the bull’s-eye.
6) Push the entire tumbler down until the top is just under the surface of the water.
7) Adjust the air flow to the tumbler to a point where the eggs are just visibly vibrating on the surface of the netting.
• Keep the number of eggs low in a tumbler. They should not sit more than 3 to 4 eggs deep on top of the net screen.
• Check the motion of the eggs and larvae often. They should move but not rise up into the tube more than 1/8 inch.
• Dead eggs or larvae should be removed. Turn off the tumbler, remove the top and suck out the dead with a piece of rigid airline tubing.
• When the larvae are actively swimming up into the tumbler column it is time to move them to a small aquarium or plastic box.