The Zebrafish Science Monitor, Vol 3 (6)
CONSTRUCTION OF ZEBRAFISH SPAWNING CAGES
By P. Ham and K. Cheng; Department of Pathology, C7804, Hershey Medical Center, 500 University Drive, Hershey, PA 17033, USA
We have received several requests for detailed instructions for construction of durable, autoclavable, economical spawning cages, which we summarize here. We use a design similar to one described by Solnica-Krezel et al. (Genetics 1994, 136:1404). The end-product is an opaque cage with a wire-mesh bottom, placed inside of a transparent cage. As the fish spawn, eggs drop through the mesh to a space in the outer cage that the adults cannot reach.
Tools required include pliers, glue gun, medium steel shears, hotplate stirrer, large file, razor blade, and carbide-tipped blade on a table saw. Materials include stainless steel wire mesh (McMaster-Carr, 9226T79; 8 x 8 per inch), 9 3/8 x 5 7/16 x 5 1/8" polycarbonate (Nalgene 6602277) and polypropylene (Nalgene No. 6621177) animal cages. Melt the plastic to the mesh in a fume hood, in case of smoke.
The steps:
1) Slowly and precisely remove the bottoms of the polypropylene cages using a carbide-tipped blade on a table saw.
2) Remove large burrs with the razor.
3) Create a template and cut wire-mesh bottoms from the stainless steel mesh using sheet metal shears. The edges of the mesh should meet the outer edges of the cage walls for a proper fit.
4) With a hot glue gun, temporarily glue the wire-mesh to the polypropylene cage bottom in about six places. We suggest liberal glue application in six spots: in the middle of one of the shorter sides, and 3-4 cm. away from each corner along the long sides. Excess glue provides a handle for subsequent glue removal.
5) Melt the wire-mesh into the bottom of the polypropylene cage on the unglued end using a hotplate. We use a Corning PC-320 hotplate stirrer at a setting of about 4, and hold the cage at both sides at an angle of approximately 30 . Softening of the plastic proceeds from the edges towards the middle; continue to press down until the two flows meet. Cooling may be accelerated on a cold surface. When a lip of melted plastic forms on the outside edge of the cage, one can push the plastic over the edges of the wire using a flat tool.
6) Melt the other sides one half length at a time, removing the temporary hot glue beforehand (remaining glue will smoke).
7) File protruding sharp edges towards the cage openings to prevent dislodging the mesh from the cages.
While using these cages for spawning zebrafish during the past three years, we have found that plastic "greens" appear to miminize trauma by providing refuge, and cloth covers help to minimize distraction of the fish by lab personnel.
The Zebrafish Science Monitor, Vol 3 (6)
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