The Basic Ecological Study On European Eel And Its Preliminary Study On Ecological Culture

Ecological culture is a kind of mode without changing water. In thisfarm system the water can be purified by the phytoplankton, zooplankton,microbial. To our advantage, resources can be saved and dissemination ofdiseases can be prevented. As a result, the pollution to the environmentcan be reduced to a large extent. In this paper we made studies on theeffects of temperature, expansive pellet feed, vitamin, lucidumpolysaccharide and nitrifying bacteria upon european eel. The mainresults are as follows:1. To study the effect of temperature on the growth of European eeland ecological structure we set five temperature scalars:22℃,24℃,26℃,28℃and30℃.The result indicated that the relative weight increase anddaily mean increase of european eel reached maximum, at12.71%and0.51%respectively, the feed coefficient reached the minimum,1.57whenthe temperature was26℃. Microbial Content tended to increase first andthen declined at each temperature.2. The effect of expansive pellet feed and powdery feed on the growthof European eel and culture water quality has been studied, The resultshowed that the relative weight gain and daily mean gain of european eelin expansive pellet feed group was lower than powdery feed group. Theywere33.34%and0.67%respectively, but its feed coefficient was higherthan powdery feed group. It was56.58%. The content of ammonianitrogen and nitrite nitrogen in expansive pellet feed group was lowerthan powdery feed group.3. The effect of vitamin on the growth of different specifications ofEuropean eel has been studied by adding the expansive pellet to the feed.The result showed that feed coefficient were decreased significantly(P<0.01). The feed coefficient of larvae and young eel were lower thancontrolled diet, at1.58and1.46respectively.4. The effect of lucidum polysaccharide on the growth of different specifications of European eel has been studied by adding to the powderyfeed. The result showed that feed coefficient were decreased significantly(P<0.01). The feed coefficient of larvae and young eel were lower thancontrol diet, at1.48and1.23respectively.5. In the European eel culture, the degradation rate of ammonianitrogen and nitrite nitrogen were investigated post application ofnitrifying bacteria and the growth of european eel was compared. Theresult indicated that the degradation rate of ammonia nitrogen and nitritenitrogen in the trial group were30.56%,31.08%and84.43%,84.58%respectively. The survival rate of the trial group was100%, higher thanthe controlled group’s87.5%. the relative weight gain and daily meangain of the trial group were significantly higher than the controlgroup(P<0.05).6. Based on the experiments mentioned above, a production test wasconducted in a pond with an area of160m2, the sediment was sandy soiland water depth was0.7m. And the weight of European eel was1000kg.After breeding for48days, the survival rates are99.44%and deathnumber is112.The feeding of diets was509.9kg, the weight gain was298.5kg and the feed efficiency was58.54%. No drug was applied inbreeding, and the daily mean quantity of exchanged water was2.91%.