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prove injurious to the fishes, many breeders 
still use them. 
Top Minnow or Leoparp Fisu (Gambusia) 
In Louisiana and Florida and Cuba and in 
fact pretty generally from Illinois to Mexico, 
top minnows inhabit the brooks and ponds, and 
Gambusia holbrooki is the proper toy fish for 
those who admire jet black or the combination 
of black and white, so striking in any animal. 
In this species the males are wholly black or 
black and white, while the females are plain 
fish-gray. (It is said that an occasional male 
is found lacking color like the females.) 
Another common species, found in Mexico, 
our own southern states, and even as far norti 
as Delaware, is G. affinis, which does well 
in a “happy family” tank of native fishes. 
Both sexes are gray. Some specimens have a 
dusky band on the sides, others are faintly 
peppered with black. 
Neither of the species mentioned exceeds two 
inches in length and in most collections the 
males are but one inch long, the females one 
and a half inches. 
In the top minnow the embryos develop in 
the evisacs, where, as a rule in viviparous spec- 
ies, they are fertilized, and deveiop in the 
ovarian cavity. It consequently happens that 
the dark area which indicates gravidness in 
most other small live-bearing species, is present 
at all times and may mean nothing in Gam- 
busia. It is therefore not so simple to make 
special preparations to save the young, which 
the parents mercilessly pursue and devour. The 
tank should be uncommonly well stocked with 
plants in which the fry may hide. 
Food for young and adults should be the 
same as for the rainbow fish. 
Tue Mvup-Earers 
The Mud-eaters (Mollienisia latipinna M. 
velifera, and M. formosa), ranging from the 
Carolinas to Mexico, accommodate themselves 
to either fresh or brackish water and_ bring 
forth their young alive. One brought to New 
York from Key West gave birth to seventy- 
five young, and another that died was opened 
and found to contain one hundred and twenty- 
eight embryos. 
They are large at birth—about three-eighths 
of an inch long—and so far as has been observed, 
the parents do not eat them. For safety’s sake, 
however, it is customary with aquarists to 
separate the young until six or eight weeks old, 
since a suspicion of cannibalism attaches to 
fishes in general. 
ZOOLOGICAL SOCIETY BULLETIN 
Altogether, the mud-eater is one of the most 
satisfactory of toy fishes, accepting almost any- 
thing offered—prepared foods, boiled egg yolk, 
chopped meat, fish, shellfish, ete., and the males 
are exceedingly attractive in the breeding season, 
adding orange tints to the head and breast that 
contrast handsomely with their steel-gray bodies 
trimmed with black lines, and frequently exhibit- 
ing for the female’s admiration their beautiful, 
sail-like dorsal fin. They are fond of vege- 
table foods also, and a dense growth of algae in 
the tanks suits them to perfection. 
They grow slowly in captivity—more slowly 
in brackish than in fresh water—but breed 
when about two years old, even though they 
have not yet attained half their growth. As 
with most fishes, there are fewer young in the 
first than in subsequent births, especially so if 
the mother is not half grown. 
The sex of the mud-eaters can be told from 
birth by the intromittent organ of the male. 
The mud-eater’s flat head gives it a peculiarly 
unintelligent expression; but except for this, the 
little fish has a comfortable, matronly look, 
which makes it appear to accept captivity with 
genuine contentment. 
Mexican Sworpratrs AND Hyprips 
Except for the rainbow fish it is probable that 
no tropical toy fish has met with so much favor 
among American aquarists as Xiphophorus hel- 
leri, the only species of the three handsome 
Mexican Swordtails (found in Mexico and Cen- 
tral America) that is commonly brought into 
the States. 
The male has a long, green or yellow sword- 
like tail edged with black, and a red stripe adorns 
his body. The female’s shape is similar to that 
of the female rainbow fish, but she is twice, 
sometimes three times as large, and much more 
beautiful, having an orange-red band running 
the length of her body. 
The two other species of swordtails are X. 
jalapae, found in the streams of Vera Cruz up 
to an altitude of five thousand feet and attain- 
ing a length of four inches, and X. montezumae, 
found in the basin of the Rio Panuco and hay- 
ing about the same length as X. helleri— about 
four inches. 
Their habits are similar to those of rainbow 
fishes, the females having been known to re- 
main fertile for over a year after one impregna- 
tion, normally producing a dozen young about 
every six weeks in water of summer temperature, 
and eating their own young unless the latter are 
protected. 
