Effects Of Water Temperature And Light On The Early Development Of The Mandarin Fish

Siniperca scherzeri is an important and valuable freshwater economic fish in my country and has always been favored by consumers.In recent years,due to environmental pollution and overfishing,the number of natural seedlings of Siniperca scherzeri is far from meeting the needs of production and market.With the advancement of artificial breeding technology,Siniperca scherzeri has been paid more and more attention as a new freshwater aquaculture object.In this paper,focusing on the biology of the early developmental stage of the Siniperca scherzeri,by analyzing the morphological and developmental characteristics,feeding and growth characteristics of the Siniperca scherzeri,the effects of water temperature and light on the early developmental stage of the Siniperca scherzeri were studied.The main findings are as follows:1.Under the indoor conditions with a photoperiod of 16 light(L): 8 dark(D),a total of 5water temperature gradient groups of 21°C,23°C,25°C,27°C and 29°C were set.The feeding rate,digestive tract fullness,satiety rate,food intake,feeding intensity,body mass growth rate,and total length growth of the Siniperca scherzeri in the early developmental stage were calculated by measuring food intake,body weight,total length,eye diameter and number of deaths.rate and eye diameter growth rate.The results showed that the optimum water temperature for early development of Siniperca scherzeri was 25°C,and the suitable water temperature range was 23-27°C.Within this temperature range,Siniperca scherzeri fry had vigorous feeding,good vigor,rapid response and fast growth.In the five temperature gradients,the food intake rate,the fullness of the digestive tract,the satiety rate,the food intake,the growth rate of body mass,the growth rate of the total length and the growth rate of the eye diameter gradually increased first and then decreased with the increase of the water temperature.Low temperature,too high or too low temperature all have a certain inhibitory effect on the early development of Siniperca scherzeri;During the 7th to 10 th day(d)of the experiment,the growth and development rate of Siniperca scherzeri fry was significantly faster than other experimental times.The results of this experiment are also consistent with the law of water temperature on the survival of fish.When the test water temperature is too high or too low than the natural temperature of the water body,the fry will die in a short time.The greater the temperature difference,the faster the death rate.This indicated that the adaptability of Siniperca scherzeri fry to changes in water temperature was positively correlated with the start and stop water temperature.In the process of artificially cultivating seedlings,when the water temperature is low,artificial warming can be used to speed up the growth and development of seedlings and shorten the breeding cycle.2.Under the indoor conditions of water temperature of 23～25℃,a total of 5 photoperiod gradient groups of 24 D,8L:16D,12L:12D,16L:8D and 24 L were set up.The feeding rate,digestive tract fullness,satiety rate,food intake,growth rate of body mass,growth rate of total length and eyes of Siniperca scherzeri in the early developmental stage were calculated by measuring food intake,body weight,total length,eye diameter and number of deaths.diameter growth rate,etc.The results showed that the optimum light period for early development of the Siniperca scherzeri was 16L:8D,and the suitable light time range was 8-16 h.Within this light time range,the fry of the Siniperca scherzeri had vigorous feeding,good vitality,rapid response and fast growth.In the 5 photoperiod gradients,the fry in the 24 D and 24 L groups had extremely low adaptability and died in large numbers in a short period of time.In 8L:16D,12L:12D and 16L:8D three photoperiod environments,feeding rate,digestive tract fullness,satiety rate,food intake,feeding intensity,body mass growth rate,total length growth rate and eye diameter growth The rate increases with the increase of water temperature;During the 4th to 7th day of the experiment,the growth and development rate of Siniperca scherzeri fry was significantly faster than other experimental times.In the process of artificial cultivation of Siniperca scherzeri seedlings,the light time can be appropriately extended to promote the growth and development of Siniperca scherzeri fry.But at the same time,the light time should not be too long,one is not conducive to the growth and survival of the Siniperca scherzeri seedlings,and the other is to increase the cost of cultivation.