NANFA-- Hybrid Fundulus?

R. W. Wolff (
Mon, 2 Dec 2002 18:17:32 -0600

I have a developing killifish that ain't right.

In my killi pond ( 9 feet by fifteen feet and about 30 inches deep) I keep
several killis and a few other odds and ends during the warm months ( which
this year was not very long ). When I harvested this fall what I thought
was a small F. sciadicus ( plains topminnow) looked sort of strange. It was
much more stout. I also had what I am pretty sure are F. rubrifrons (
Redfaced topminnow) since they look different from cingulatus I have from a
location that only has cingulatus, where as this fish came from the overlap
of the two. I only had a couple young retrieved from these. Both species
spawn in the same manner, use the same displays, and the males will display
to each others females. The females always seemed to be able to know who to
follow to the weed clumps after the display, as long as I was watching them
anyways. The display consists of fighting another male, fins and gills
flared, and the color turned up to 10. Then the male that wins this open
water match will stay there and fling droplets of water across the surface.
This is much the same thing many topminnows do when scared to divert
attention from themselves. Anyways, the odd looking one is now developing
colors consistent with being in between these two fish. Old literature I
have say sciadicus is in subgenus zygonectes ( spelling?) along with the
rubrifrons and others. Newer stuff I read puts sciadicus in xenisima (
spelling?) the studfish subgenus. I would say how they act would make them
more like the rubrifrons and chrysotus than caetnatus or stellifer. But they
do look sort of like a studfish up close, but then again they look like a
topminnow as well.
Has anyone heard of the freshwater Fundulus hybridizing? (I have read of
diaphanus diaphanus hybrids with heteroclitus.) These two species do not
occur together in nature. Both have reddish fins trimed in black, and a gold
stripe in front of the dorsal fin. They are kind of hard to tell apart from
a distance. Females are really close, with sciadicus more streamlined and a
longer snout, and rubrifrons females have a gold iridesence on the cheek. I
will continue to watch him as he grows and see what he looks like at a more
mature size. Right now he is only just over an inch, but fully colored in
comparison to a sciadicus, and nearly compared to the rubrifrons.
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