| Odontobutis potamophlia and Odontobutis yaluensis both belong to Odontobutis. O. potamophlia and O. yaluensis have fine and tender meat. They are delicious and nutrient-rich, which are people’s favorite. They have a wide development and utilization prospect, and they have been the important artificial breeding commercial fishes in our country, but at present, the artificial breeding technique for Odontobutis is still unstable and the key techniques for the artificial breeding of such kind of fish are badly needed. This paper studies key factors in the process of artificial breeding of O. potamophlia and provides important references for the large-scale artificial breeding of it At the same time, through cloning the whole length of O. yaluensis mtDNA and the analysis of its structural features, it establishes the phylogenetic tree of 22 kinds of Perciformes including O. potamophlia and O. yaluensis and provides basic data for the study on phylogenetic relationship and origin, as well as evolution. The main results were shown as follows:1. Early-reproducing experiment on O. potamophliaIn November, choose O. potamophlias of more than one year old as the parents and breed them indoors with rising temperature, making the temperature for parents higher than the outdoor water temperature of the corresponding period. After the twenty one-day cumulative temperature cultivation at different temperatures, dissect the parents and it finds that about half of the female parent’s eggs are spherical shape, semitransparent, faint yellow or golden yellow. The spermary of male O. potamophlia is milk white, plump and bright. That is to say, gonads of the parent fish grow quickly and the gonads have been mature and could breed O. potamophlia in advance. O. potamophlia egg laying amount reaches the maximum when they are cultivated in the water of 24℃ and a couple ofparent fish could lay 1,547 eggs.2. The effect of temperature on the embryonic development of O. potamophliaPut the embryos of O. potamophlia at different temperatures (15,18,21,24,27and 30℃) to be fertilized and develop. Observe and record the time needed to grow to different periods under a microscope. Results show that with the lowering of temperature, the development process of embryos is getting slower and slower. When the temperature drops to and under 15℃, some of the oosperms stagnate at the blastula period to the gastrula period before hatching and they could not grow regularly to the hatch. Within the temperature range of 15-30℃, with the rising of temperature, the time O. potamophlia embryos need to grow to each period are getting shorter and shorter, but when the temperature reaches 30℃, many embryos have deformity in the development and die at the segmentation period in succession. When the temperature is 27℃, although embryos develops quickly, the deformity rate is relatively high, reaching 9.7%; when the temperature is between 18℃ and 24℃, only few embryos have malformation. Through the comparison of hatching rates at different temperatures, it finds that the hatching rate is the highest (83.7%) at 24℃; the hatching rate is also quite high(above 70%) at 18and 21℃; the hatching rate is relatively low(40%-60%) at 15℃ and 27℃. The hatching rate reaches the lowest (only13%) at 30℃. Synthesizing factors like incubation time, hatching rate and deformity rate,21℃ to 24℃ is the optimum temperature range for the development of O. potamophlia embryos.3. The prevention and treatment for saprolegniasis of O. potamophlia zygotesChoose O. potamophlia zygotes that normally develop and treat them respectively with 2.0,4.0,8.0,16.0 and 32.0mg/L KMnO4 solution, C16H18ClN3S solution and NaCl solution and observe the development situation of zygotes. Through the experiment, it finds that when the concentration of C16H18CIN3S solution ranges from 8.0-32.0mg/L, the saprolegniasis infection rate of embryos is below 10%,; when the concentration of NaCl solution ranges from 16.0-32.0mg/L, the embryos mildew rate is lower than 10%; when the concentration of KMnO4 solution ranges from 2.0-32.0mg/L, the embryos’ mildew rate is always higher than 40%. Therefore, it suggests that C16H18CN3 and NaCl solution in high concentration could both effectively control the saprolegniasis, but the hatching rate of O. potamophlia zygotes treated with NaCl solution in high concentration is below 20%. But when the concentration of C16H18CIN3 solution is between 4.0 and 8.0mg/L, the hatching rate is above 80%. Synthesizing the infection rate and hatching rate, C16H18CN3 has the best effect on the prevention and treatment for saprolegniasis of O. potamophlia embryos.4. The effect of salinity on the survival and growth of juvenile O. potamophliaThrough setting six groups of different salinities (0.0,2.0,4.0,6.0,8.0 andl0%o) and research on their influences on the survival and growth of juvenile O. potamophlia, it finds that the specific growth rates of O. potamophlia at different salinities are 4.0> 2.0> 6.0> 8.0>10.0>0.0‰ in sequence of higher to lower. When the salinity is 4.0‰, the specific growth rate is the highest, namely, the juvenile O. potamophlia grows fastest at 4.0%o of salinity. When the salinity is 0%o, the juvenile O. potamophlia grows significantly slower than the others at different salinities. With the passing time, the differences of the specific growth rates among different salinities gradually decreases, namely, the low salinity water stimulates the rapid growth of juvenile O. potamophlia. When the salinity ranges from 2.0%o-6.0‰, the survival rate change of O. potamophlia in 35d is between 61.67% and 85.00%. When the salinity is 10.0%o, the survival rate is relatively low, only 13.33%; when the salinity is 0.0%o, the survival rate is 73.33%. It suggests that within the salinity range from 0.0 to 6.0%o, the juvenile O. potamophlia could normally survive and grow. Synthesizing the survival rate and specific growth rate, and within the salinity range from 2.0%o to 4.0%o, the juvenile O. potamophlia could grow the fastest and has relatively high survival rate.5. Cloning the whole length of O. yaluensis mitochondrial DNAO. yaluensis mitochondrial DNA sequence is obtained through the PCR cloning technique, and the overall length is 16,909bp. It consists of 13 protein genes,22 tRNA genes,2 rRNA genes and 2 segments of main noncoding regions:the light chain’s duplication initial zone and control zone(D-loop) and the noncoding sequences spreading among genes. The sequence basic group content in O. yaluensis mt DNA is A (30.48%), C (28.99%), G (15.28%),T (25.25%) and similar to many of the vertebrate, the content of A and T (55.73%) is a little higher than GC.6. Study on the phyletic evolution relationship of Odontobutidae based on the whole length of the mitochondria DNA sequenceRetrieve and download the published 21 kinds of Odontobutidae mitochondria whole genome sequences from the GenBank database (http://www.ncbi.nlm.nih.gov/). Using the software of MEGA5.0, establish the phylogenetic tree with the adjacent method of NJ and ML with the clonal O. yaluensis mtDNA in this paper. The maximum genetic distance between O. sinensis and Synechogobius ommaturus is 0.333, and the minimum genetic distance between Oxyeleotris marmorata and Oxyeleotris lineolatus is 0.022. The genetic distance between O. yaluensis and O. potamophlia is 0.092, and the genetic distance between O. potamophlia, O. yaluensis, O. sinensis and O. platycephala is 0.092-0.192, which suggests that among the four common kinds of Eleotridae, O. potamophlia and O. yaluensis has the closest genetic relationship.
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