Zebrafish will mate
and deposit fertilized eggs on the bottom of the tank at
'dawn'. They can be accustomed to lay at any convenient time
by keeping the room dark and lighting the tank with a timer.
The maximum embryo production is obtained with a ratio of 1
male for every 2 females, with a group of 20-25 fish. The
night before embryo collection, vacuum the tank well with a
siphon to remove debris several hours after the last
feeding. Deposit a layer of washed marbles to cover the
entire bottom surface of the tank. Do not disturb for the
first 30 minutes after 'dawn' to allow fish to mate (see
below). Embryos can be collected once a week, with best
results from tanks kept on a regular schedule. Collect
embryos and fertilized eggs from between the marbles with a
siphon and collect with a fine fry net or mesh filter.
Transfer the net to a glass dish full of tank water and
examine the embryos with a dissecting microscope at low
magnification. Transfer healthy embryos to a clean glass
petri dish containing embryo
large-bore glass pasteur pipets. Discard any that are cloudy
or ruptured. Keep embryos at 28°C.