Fish Maintenance and Egg Collection

1. Fish are raised in a temperature-controlled room maintained at 26-28.5°C and on a 14-h light:10-h dark cycle. The main room lights switch on at 9:00 am, but some tanks are blacked out with respect to the room lighting and have their own lights, which are kept on a similar light/dark cycle but with their lights set to come on at 10:00 am, 11:00 am, and 12:00 am.

2. Eggs are collected using a polyethylene sandwich box with a rectangular hole cut out of the lid. The hole is covered with nylon mesh with a pore size of about 3 mm. The mesh is fixed to the lid with aquarium sealer. The mesh also has a few 10-cm strands of green plastic garden twine attached to simulate foliage. One of these boxes is placed in each 50-L tank, and the fish spawn among the plastic twine. The box is weighted down with a few glass marbles on the lid.

3. Ten to 25 fish are placed in the tanks at least a day before egg collections. They should be 6- to 12-mo old, and approximately twice as many females as males. The collection boxes are placed in the tank the evening before the eggs are required. Spawning occurs when the lights go on and can continue for 2-3 h.

4. The collecting boxes are removed and replaced at 15-30 min intervals.

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