Page 162 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

160 FRESHWATER FISH DIRECTORY

Xiphophorus hellerii
Swordtail

ORIGINS Central America, ranging down the Atlantic
side from Mexico to northwestern Honduras.
SIZE 4 in (10 cm).
DIET Prepared foods and small live foods.
WATER Temperature 70–77°F (21–25°C); hard
(100–150 mg/l) and alkaline (pH 7.5).
TEMPERAMENT Males are often quarrelsome.
In common with most domesticated livebearers, Female
the Swordtail’s color and pattern are very
different from those of the wild type. Many
of these fish have a hybrid ancestry, thanks to
earlier crossings both with other types of
swordtail and also with platies (see p.162).
Wild swordtails are usually quite plain-looking
and greenish, blue, or reddish in coloration,
while some display blotched patterning. Wild
populations can vary significantly in
appearance from place to place.
In aquarium surroundings, Male
mature male swordtails are
aggressive toward one another. It is
relatively straightforward to identify the name of these livebearers derives Golden Comet Swordtail The black tail
potential troublemakers, since only the males from xiphos, the Greek word for “sword.”) streaks are called the comet characteristic.
possess the impressive swordlike extension to Females, which are larger than males, sometimes Golden Swordtails tend to be less brightly
the lower rays of the caudal fin. (The scientific develop the sword, too, as a result of hormonal colored than red forms. The broader body of
changes. These individuals, however, are the female can be seen in this pair.
unable to reproduce as males.
Reddish-spotted
dorsal fin Swordtails can prove to be quite prolific when Dorsal fin has
breeding; larger females produce as many as an extension Lyre-tailed fin with
200 fry in a single brood and can repeat this symmetrical swords
feat every month or so. However, if the young
are to survive, the female must be transferred
to a breeding trap in a suitable nursery tank.
Few livebearers are more notorious for hunting
down and cannibalizing their offspring than
Black Calico Swordtail This
form was developed in the swordtails. The young are relatively simple to
Male’s sword- laboratory. The black gene is rear on their own if provided with items such Red Wag Lyre Swordtail The caudal fin has a
like extension linked to tumor formation. as fry foods and brine shrimp. sword on both its upper and lower rays, while its
black coloration contrasts with the reddish color of
the body. The lips are also black.

Gonopodium
confirms that Sword visible in
this is a male this young male
Pineapple Swordtail The appearance of this very popular
form varies from yellow to intense red. The depth of the
Pineapple Swordtail’s coloration can be improved by
color-feeding.

Green Swordtail (left) These fish are the ancestors of
today’s domesticated varieties, but their subdued
coloration means they are not as widely kept. The
patterning varies throughout their natural range.

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