Hi,
I was in my local fish store the other day and I noticed there was 2 Siamese fighters in one tank, there was definatly one male but the other one you couldn't really tell, cause his/her tail wasn't as long as a male but wasn't as short as most females,
the fish was stunning so I was thinking about buying it, but I asked someone in th store whether it was male or female, and he said it was a feminate male - now is that possible?
I didn 't buy it in the end cause I didn't know what to think when he said that. I told my mum who is more a fish person than me (I'm new to the hobby) and even she was slighly confused by what she said.
I was actually putting something together to post elsewhere, then came across this post.
These are two examples of a relatively new and frightening situation rapidly becoming common - not just in fish, either.
http
/www.ourstolenfuture.org/NewScience/...ooksexratio.htm
' Nagler JJ, J Bouma, GH Thorgaard, and DD Dauble. 2001. High Incidence of a Male-Specific Genetic Marker in Phenotypic Female Chinook Salmon from the Columbia River. Environmental Health Perspectives 109:67-69. '
'Nagler et al. report an unexpectedly and unusually high proportion of wild chinook salmon that appear to have been sex-reversed early in development: chromosomal males that have female reproductive tracts. Genetically-similar hatchery-raised salmon in another river show no such effect. This research raises the question as to whether widespread sex-reversal may be contributing to the decline in wild salmon populations in the Pacific Northwest.
'Feminization of male fish has been focal point of concern about endocrine disruption since the early 1990s. While the phenomenon was first discovered in England, it is now also known to occur widely in Europe and in the United States. This paper is the first to report feminization in an endangered salmon. It is also striking because of the high proportion of feminized males and the degree to which sex reversal has gone: many of the males are fully fertile females.
'Experiments with other species of fish have shown that exposure of fish eggs to estrogen-mimicking substances can cause complete sex reversal of males to fertile females. ...'
'... An estrogen-sensitive "window" in salmonids occurs around the time of hatching and extends to beyond the time when these fish begin to feed exogenously; during this window male chinook salmon have been shown to be very susceptible to sex reversal. Early during this estrogen-sensitive period (at or shortly after hatching) male chinook salmon can be sex reversed by exposure to high concentrations of estrogen for periods as short as one hour. ...
'It is possible that wild chinook salmon in the Hanford Reach were exposed to estrogens or compounds that mimic the biological activity of estrogens--the so-called environmental estrogens that have caused sex reversal in some genotypic males. Environmental estrogens are chemicals in the form of detergents, plasticizers, and pesticides that derive from a wide range of human activities, such as industry, agriculture, and domestic sewage processing. Some of these compounds (e.g., atrazine, carbofuran, lindane, methyl parathion, and dieldrin), known to be estrogenic in rainbow trout (O. mykiss) bioassays, are present in the Columbia River. The compounds identified have been detected throughout the year in waters of the Hanford Reach at annually stable but low levels (> 1-6 ng/L)
'Nagler et al. go on to speculate that it is possible that the small percentage of "real" females in the wild chinook sample were from an upstream hatchery. They also note that the offspring spawned by mating of real males with sex-reversed males would be either XY or YY instead of all XY, the outcome of normal male to normal female mating. YY would never happen normally. This would lead to a steady decrease in the number of normal females in the population. The fact that only 16% of females were normal (and some if not all of those may have been hatchery, not wild), appears consistent with that prediction.'
http/www.cfr.washington.edu/classes.esc....nedisruptor.doc
(Must open file)
Study links river pollution to 'feminization' of male fish
by Marla Cone
Los Angeles Times
'In a surprising scientific discovery that suggests pollution is feminizing animals in the wild, sewage in rivers appears to contain estrogenlike chemicals potent enough to cause fish to be born half-male, half-female.
'The finding by British scientists provides strong new evidence that hormone-altering pollution could be a global ecological threat.
'Other recent studies had found scattered populations of animals with sexual defects living in highly polluted waters, but the new research suggests that the problems are more widespread than previously detected. ...'
"The incidence and severity of intersexuality . . . is both alarming and intriguing," researchers from Brunel University and the British government reported in the September issue of the journal Environmental Science and Technology.
Some male fish have such mixed-up hormones that they are born with ovaries and eggs instead of sperm ducts. In two of the eight rivers downstream of sewage-treatment plants, all of the male fish sampled had feminized reproductive tracts. The other six rivers had rates from 20 percent to 80 percent.
Hundreds of widely used man-made chemicals - including pesticides, industrial compounds, dioxins and ingredients of plastics and detergents - are believed to mimic estrogen or block testosterone, disrupting the endocrine system that is critical to sexual development.
In their report, the scientists called their findings "the first documented example of a widespread sexual disruption in wild populations of any vertebrate." Hormonal havoc, however, has previously been reported in alligators, birds, river otters, carp and other U.S. wildlife in isolated locations.
The phenomenon of "intersex" animals was first discovered in the 1970s, but it was dismissed as a fluke until the early 1990s, when biologists found feminized alligators in a polluted Florida lake and began to suspect that man-made chemicals were altering sex hormones. ...'
'... The reproductive damage might have dire consequences for an ecosystem, because if males are sterile, an entire animal population might gradually be depleted. Fish, in particular, are an important link in the world's food chain.
So far, the fish in the British study - a species called "roaches" - remain abundant, even in the Aire and Nene rivers, where all of the tested males were feminized. Apparently some of the males still have enough of their systems intact to reproduce.
"What we still don't know is if these intersex fish are reproductive or not. That's the bottom line," Weis said. "Some of them have no sperm ducts, so obviously they can't reproduce."
Because females are more critical to reproduction than males, populations can regenerate themselves even if only a few males are fertile. Over the generations, though, if feminization remains unchecked, fisheries could collapse. '
A feminized male betta is apparently no longer uncommon.
