Page 163 - Encyclopedia of Aquarium and Pond Fish, 3rd Edition

LIVEBEARERS/SWORDTAILS 161

Xiphophorus birchmanni Xiphophorus montezumae
Sheephead Swordtail Montezuma Swordtail stock is rarely available today. Males have a
larger dorsal fin than females, although they are
ORIGINS Central America, occurring in various ORIGINS Central America, restricted to eastern Mexico, otherwise slightly smaller in size. Their broods
waterways around Hidalgo, Veracruz, Mexico. in the states of Tamaulipas and San Luis Potosi. average about 50 fry, with the interval between
SIZE 3 in (7.5 cm). SIZE 3 in (7.5 cm). broods usually being about seven weeks, although
DIET Prepared foods and small live foods. DIET Prepared foods and small live foods. seasonal factors may affect their breeding
WATER Temperature 70–77°F (21–25°C); hard WATER Temperature 70–77°F (21–25°C); hard behavior. The Montezuma Swordtail is not
(100–150 mg/l) and alkaline (pH 7.5). (100–150 mg/l) and alkaline (pH 7.5). especially brightly colored, although there can be
TEMPERAMENT Males are often quarrelsome. TEMPERAMENT Males are often quarrelsome. individual exceptions. Typically, these fish are
bluish-silver and display a pattern of dark spots on
This swordtail species is unusual, because the male The key feature of the Montezuma Swordtail is the flanks. The sword of the male is often greenish
has no trace of a sword on his caudal fin. He can the way in which the male’s sword projects almost or yellow, with fairly prominent black edging. It is
still be easily distinguished from the female by his horizontally, rather than downward as in other important not to keep these or other swordtails in
gonopodium and larger dorsal fin. Well-oxygenated swordtails. The length of the sword varies in fish the company of fin-nipping species, because their
water is important for this species, which has only from different populations, although wild-type swords will inevitably be attacked. In addition,
been available to hobbyists since about 1990. The their aquarium needs to incorporate plenty of
broods are small, typically consisting of 10–35 fry. open swimming areas so that they do not
damage their swords in confined spaces.
Mottled
dorsal fin

Gonopodium
of male
Slightly curved caudal fin

PREVENTING A SERIOUS DUEL

One way of reducing aggression between male
swordtails is to house them in a mixed group. There
is still likely to be intermittent squabbling, but the
disputes will not be as fierce. The swordtails will
also be less likely to bully other tank
occupants. Avoid mixing swordtail
species, because hybridization is
likely and there will be conflict
between the different males. Equally,
they should not be kept alongside platies,
with which swordtails will readily interbreed.

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