Cyprinodontiformes vivíparos e ovovivíparos
Artigos - O Tesouro Perdido dos Aztecas
Articles - The Lost Treasure of the Aztecs
The Lost Treasure of the Aztecs
James K. Langhammer - published at this website in March 2009
( This is an article originally written in 1976 and
published in Tropic Tank Talk of the Greater Detroit Aquarium
Society and in Livebearers of the American Livebearer
Association. It was revised in 1982, in 1999, and again in 2007.
It is the first part of a series by the same title ).
Yet history also alludes to the fact that the New World's ultimate treasures as envisioned by the Spaniards were never found.
Why ? Where were they hidden - and by whom ?
Perhaps, the real treasures of the Aztec empire were hidden to the Europeans by their own inconsummate greed, and have continued so to this day! Gold and gem-stone ornaments were probably more beautiful than valuable to the Aztec people whose artifacts reflect the great majesty of the natural world around them.
Part of the beautiful baubles of the everyday world of the Aztecs still shimmer in the hot sun of the Tropic of Cancer, vicariously reflecting the Sun-god's radiance off their animate flanks in a brilliant blend of opalescence and pigmentation, and STILL are unknown and unappreciated by the modern world ! - the goodeids, a fascinating family whose livebearing species are restricted to Mexico. Equally fascinating is how habitat destruction has impacted the less colourful EGG-LAYING goodeids of the genera Empetrichthys and Crenichthys. These two ancestral remnants are the last living examples of the early evolution of the family Goodeidae. Both egg-laying genera are critically endangered and really need hobby exposure. But be aware that since they are US natives, they cannot be legally acquired nor husbanded by private aquarists under our current laws.
livebearing subfamily Goodeinae is restricted to the ancient Aztec
domain of west-central Mexico. Using the state capitals of Durango,
Colima, Morelia, Mexico City, Queretaro, and San Luis Potosi as boundary
references, the total range of the subfamily which consists of
approximately 36 species in 17 genera can be roughly circumscribed.
Certain river and stream species, such as the Ilyodon Eigenmann, are swift swimmers with slim, streamlined bodies and large caudal fins.
In ponds, lakes, or quiet stream pools, deep-bodied forms, such as Skiffia Meek, are slow moving and manoeuvre easily in dense vegetation, sculling with the pectoral fins in a manner reminiscent of many resident coral-reef fishes.
Members of the genus Allodontichthys Hubbs and Turner look and behave like North American darters ( Etheostomatinae ), are long-bodied bottom dwellers, and are found only among the rocks and boulders in shallow riffles.
Goodeids include all consumer types : carnivores with conic teeth and a short gut, Alloophorus; herbivores with generalized bifid teeth and a long coiled gut, Ameca Miller and Fitzsimons; or omnivores with variable teeth and gut form, Xenotoca Hubbs and Turner, the feeding habits of which range from nearly completely carnivorous to completely herbivorous at different localities.
The first six or seven rays of the male anal fin are crowded, shortened, and often separated from the rest of the fin by a distinct notch; they probably aid in insemination. The anterior anal rays of the male have been described as a “ gonopodium ” (Turner, Mendoza, and Reiter, 1962), a term first applied to the elongate male anal fin of the poeciliids, but this term may be a misnomer for goodeids since the role of the anal fin in sperm intromission has not been demonstrated ( Miller and Fitzsimons, 1971 ).
Goodeid males also have a short, highly muscular tube connecting the sperm ducts to the genital opening; this structure has been termed a “ pseudophallus ” ( Mohsen, 1961, 1965 ). It is said to expel semen forcibly or to become everted and applied to or placed into the female's genital opening, but, as with the “ gonopodium ”, its function has only been surmised and not demonstrated.
Females have a single median ovary formed from the union of lateral organ rudiments, the fused internal walls of which form the median septum.
Yolk is reabsorbed early in embryogeny and its nutritive function is assumed by placenta-like trophotaeniae, rosette or ribbon-like growths which extend from the anal region of developing embryos in all but one species ( Turner, 1933, 1937 ). ” - end of Fitzsimons quote.
It is true of all goodeids and many fishes generally that body pigmentation may be enhanced by iridescence reflected from light sources back to the viewer - resulting in visual splendour not seen if the fish are viewed in poorly lighted situations. Rainbows are relatively peaceful with other fishes -although as with all goodeids some fin-nipping of other fishes seems to occur if the goodeids are not regularly fed well.
Generally goodeids do not cannibalize their own young unless the parents
are inadequately fed and maintained; thus multiple generations are
easily exhibited together. Goodeid populations should be housed
separately, however, since some interspecific hybridization has been
documented ( Fitzsimons, 1972 ).
Detroit water with pH of about 7.2 and 120 ppm of carbonate, a downward
shift in pH can quickly become fatal to goodeids. I believe hard,
alkaline waters are much more to their well-being.
are peaceful and seem more tolerant of old water than most goodeids are.
It is a slender fish growing to 100 mm. On the flanks are two parallel, horizontal stripes and in the male the caudal fin is a beautiful pastel blue by reflected light.
Blue-tailed Goodeid is sensitive to water quality. It is the most
easterly of all goodeids and it alone lacks the well-developed
trophotaeniae so characteristic of goodeids; for that reason it was once
considered the most primitive member of the family. Recent research
suggests instead that the trophotaeniae were lost as Ataeniobius evolved
from the genus Goodea. It is one of the few species in which I cannot
see sexual dimorphism at birth; visible anal-fin modification in males
seems to occur at about 30 mm.
The dorsal and anal fins of males are picoted ( or bordered ) in orange which can be deepened to blood-red if enough carotenoids are fed to the fish; the caudal is colourless.
The body of both sexes is boldly marked by large blotches. Behaviour is spritely but peaceful.
recent introduction and equally handsome is the Crescent Goodeid -
Zoogoneticus tequila. It is slightly more robust but differs in fin
coloration - its dorsal and anal fins are bordered by creamy bands and
it is the caudal fin which is bordered by red-orange!
Red-tail is a pugnacious, astonishingly fecund, hardy, and robust
species which grows to 80 mm. and seems to quickly wear out it's welcome
for most aquarists. Please, however, keep in mind that this fish is a
rogue species and not at all typical of the family.
male Jewelled Goodeid has a “ crazy quilt ” effect of opalescence on its
sides - pinks, greens, blues - which can only be appreciated by light
reflected to the viewer. The creamy yellow tail border loses effect by
not having a contrasting sub marginal band. Like the Red-tail, it grows
to 80 mm. but seems to be a much gentler and acceptable community fish.
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