Paradise Fish (Macropodus Opercularis)
The Paradise Fish (Macropodus opercularis) is naturally distributed in western Taiwan, but is
rare now because of such factors as environment pollution and habitat loss. Conservation
of this animal in Taiwan is becoming more urgent. Some closely related species, such as
Chinese paradise fish (M. chinensis), are difficult to distinguish with morphological characters. We sequenced and compared the control region of mitochondrial DNA (mtDNA) to reveal the genetic distance and molecular phylogeny of paradise fish populations from different geographical regions: Taiwan, Singapore, and mainland China.
The interspecific distance between M. opercularis (Taiwan, Singapore) and M. chinensis (Zhejiang, Jilin) is 0.1341 ±0.0124, much more highly divergent than the distance between the Taiwanese and Singaporean populations, or within the Chinese populations. Five haplotypes from 11 specimens of the Taiwanese native population have been identified from a 1034-bp-length of mtDNA. However, the lower haplotypic diversity (H = 0.68) indicates a decreasing population in Taiwan, in contrast with the M. chinensis (H = 0.89). In addition, the unique genotype in Miaoli and Taichung may imply their subdivision because of exotic input of fish from a different geographic region. Thus conservation work should focus on avoiding the random release of paradise fishes into the wild.
Effects of temperature and floating materials on breeding by the paradise fish (Macropodus opercularis) in the non-reproductive season. Zoological Studies 45(4): 475-482. The paradise fish, Macropodus opercularis, is native to Taiwan, and its reproductive season spans from Mar. to Oct. This experiment was conducted to examine Paradise Fish breeding in winter, a non-reproductive season, using different treatments of water temperatures (23, 27, and 31C) and floating materials (floating ferns, green Styrofoam pieces, and no floating material). The fish built 1-3 bubble nests during the 20 d experimental period. A significant negative correlation was found between the temperature and the frequency of nest building, indicating that a high water temperature of 31 C was unfavorable for building nests.
In the treatments with floating ferns and green Styrofoam pieces, the paradise fish built more nests than in the treatment without floating materials. The sizes of the 1st bubble nests built were significantly larger at 27 and 31..C than at 23..C. Floating materials played an important role after the fish acclimated to the temperature. In the treatment with green Styrofoam pieces, the fish built smaller-sized 2nd nests than in the treatment without floating materials. One female in a tank treated at 27..C with green Styrofoam pieces laid 421 eggs during the 20 d experimental period. Two hundred and eighty larvae hatched the next day, for a hatching rate of 66.5%. In short, the paradise fish can breed at appropriate temperatures, such as 27..C, in winter, normally a non-reproductive season, and artificial floating materials are conducive to successful reproduction.
The Paradise Fish, Macropodus opercularis (Linnaeus), belongs to the family Anabantidae in which most of the members are..bubble-nest.. builders. This species is characterized by the presence of a labyrinthiform organ, which is derived from the 1st gill arch and enables the fish to breathe in the air. Floating plants are usually dominant in spawning areas of the fish. Plants or other substrates are necessary to hold the nest in place. The paradise fish sexually matures at approximately 6 mo, breeds well in aquaria, and reaches a maximum size of approximately 80-100 mm in standard length.
The paradise fish is native to China and nearby islands. It is widely distributed in eastern Asia from the Yangtze River basin to Hainan I. in China, as well as Taiwan and North Vietnam (Freyhof and Herder 2002). The range of the fish, is habitation is 20-30 N and 102-122 E, and its climatic temperature range of 16-26 C indicates that it is a subtropical and temperate fish. Indigenous to Taiwan, it is commonly known as the Formosan fighting fish, three-spot fish, and Chinese unicorn fish (Chen and Fang 1999, Shao and Chen 2003). Prior to the mid-1970s, the fish was widely distributed in lowland areas of Taiwan where it inhabited bodies of fresh water ranging in size from rice paddy fields to lakes.
Temperature is one of the most potent environmental factors that influence the development and growth of fish. Food intake, catabolism, and conversion rates of the food consumed by fish vary with body temperature. The body temperatures of most fish are close to and do not exceed 1..C difference from the ambient water temperature, suggesting that water temperature plays an important role in the life of fish. In temperate regions, the timing of reproduction in annually spawning species is controlled by an endogenous cycle that in turn is entrained by environmental cues. Water temperature is one of the most important annual environmental cues.