Biological Characteristics Of Tanichthys Albonubes And Its Prospect Of Being Laboratory Animal

Tanichthys albonubs is a small cyprinid fish which has been found in white cloud mountain, Guangzhou, China, 1932. Distributing in white cloud mountain and rivulet of North River only, it is one of endemic fishes in South China. Going with the local environment has been destroyed, it has not been found since 1980s in fields. Fortunately, it was brought to the west countries as a kind of aquarium fishes since it has been found, so it was reared out of its distributing fields. Its english name is white cloud mountain minnow, and it has been protected by the law since 1988 in China and researchers had tried to bring it back to its native living side in 2001.Biological characteristics of T. albonubes and its prospect of being lab animal are studied in this paper. The results indicated that the eggs of T. albonubs are ashesive, nearly spherical, diameter 1.016+ 0.0.001 mm in early gastrula. The embryonic development can be divided into 28 developmental stages. Duration of the embryonic lasts about 50 hours at the temperature of 22.5-25.0℃, during which the morula multicellular form in the cleavage processing, and the embryonic rings mainly appear in the gastrula. It is prolonged largely by low temperature and accelerated by high temperature. The duration lasts 28, 50 and 147 hours at the water temperature of 28.0-30.0℃, 22.5-25.0℃ and 14.0-16.8℃.The yolk-sac larvae of T. albonubes were reared from March to June 2004 to exam the changes in feeding ability and growth during early development and starvation. The water temperature was 24.0-28.0℃. The results showed that: (1)eyes, mouth, digestive tracts, anus and the pectoral fins in 3-day larvae became functional, and the cruising swimming was formed. Larvae began to have the feeding ability. The yolk was absorbed largely, and the volume had been changed from 0. 0589 mm3 to 0.0057 mm3. Yolk was absorbed completely in 5-day unfed larvae, which began to suffer starvation. The equation relating growth in length(L) to the volume of yolk-sac in days (d) over 5-days post-hatching for the unfed larvae was L(mm) = -0.0494x(mm3) + 0.1999. The equation relating the volume of yolk-sac to age in days (d) over 5-day period post-hatching for the fed larvae was V(mm3) = -0.016d + 0.0741. (2)The initial feeding rate in 3-day larvae were up to 33.3-66.7%. 4-day unfed larvae reached the highest initial feeding rate, up to 100%, and this highest initial feeding rate lasted for 4-6 days. After hatching 9-10 days, the initial feeding rate of the unfed larvae was lower than 50%, which was the point-of-no-return (PNR). After passing the PNR, starved larvae not only entered a negative growth phase, but also showed a decrease in size of various organs, and the pectoral girdle projected markedly andformed the pectoral angle. After hatching 11-12 days later, all unfed larvae died. The characteristic of changing of feeding intensity was similar with the initial feeding rates. 0 to 2 day larvae didn't have the feeding ability yet. 3-day larvae could prey paramecium, Paramecium caudatum only 7.7. 5-day larvae reached the highest feeding intensity, which preyed the paramecium, up to 49.4, and then declined. After hatching 10 days, feeding intensity became 0. Feeding ability of larvae was deprived by the starvation. (3)The mean growth rate was 0.430 mm/day for larvae living on yolk(0-3 day) and 0.05 mm/day when the larvae reach the external feeding stage but no food was available(3-9 day). When fed on paramecium the mean growth rate was 0.244 mm/d for the larvae during the feeding stage (3-9 day). The equation relating growth in length(L) to age in days (day) over 15-day period post-hatching for the fed larvae was L (mm) = 0.2786d+ 2.4837. The equation relating growth in length(L) to age in days (d) total 11-days they could live post-hatching for the unfed larvae was L (mm)= 0.4833Ln(d) + 2.8355. (4) Over the 15-days after hatching, delayed feeding 1 day could effect the growth rates of larvae remarkably. Delayed feeding 2 day, the larvae processed the completely compensatory growth, and the total lengt...