NANFA-- Breeding Pimephales promelas (Fathead minnows)
Tue, 14 Nov 2000 08:35:21 -0600

We raised our own fathead minnows for whole effluent toxicity tests for
about 8 years. In the event these techniques are of any interest to y'all,
here's how we did it.

Fatheads are actually pretty easy to spawn. We maintained the culture room
at 25 deg. C (+ or - 2 deg. C) and used a 16 hour light / 8 hour dark

Sexually mature males and females were taken from a 50 gallon holding
aquarium and placed in 10 gallon spawning aquaria. A simple box filter
with floss and activated carbon (along with frequent water changes)
sufficed to keep the tanks clean. We used aged tap water in all tanks.

We tried to get 2 males and 8 females per tank. Sometimes what we thought
were females colored up upon introduction to the spawning tank, however,
revealing that they were actually males. As a result, we would check the
spawning tanks daily and remove or add fish until the proper sex ratio was

For spawning substrate we used 4 inch PVC cut into 6 inch sections, and
then halved down the middle to form a pair of U shaped half tubes , kind of
like this ( ). Four of these "tiles" were placed in each 10 gallon
aquarium, with the rounded side up.

Each male would stake out 2 of the tiles and allow the females to enter as
they were ready to spawn. The tiles were checked daily and those with eggs
attached (to the underside) were removed and replaced. Each spawning group
was generally good for a month or so before they were replaced with "fresh"

Egg bearing tiles were removed from the spawning aquaria and placed on end
in round plastic 1 gallon aquaria, open sides facing, with an airstone
bubbling vigorously in the center. Egg patches were checked daily for
fungal infestations and damaged eggs were removed or whole tiles discarded,
depending on the extent of infestation.

About a week after deposition the eggs would begin hatching off the tiles.
Fatheads don't start out with much of a food reserve so it is crucial to
have a food source immediately available. They also don't have very large
mouths, so it is equally important that the food be small. We used newly
hatched (less than 24 hours old) brine shrimp (Artemia) which had been
thoroughly washed with fresh water. Turn down the air in the hatching
aquaria or the fathead fry will be tumbling too wildly to successfully
negotiate the capture of the nauplii.

After a few weeks of Artemia nauplii the fry are ready for larger (and
cheaper) food fare. We used (I think) # 1 trout chow, or whatever the
smallest size is.

Hope this info is of assistance to someone!

Steve Haslouer
Kansas Division of Environment

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