Ultrasonic Application In The Aquaculture And Breeding Of Red Tilapia

Through small water bodies trials,this paper researched on the effects of different frequencies of ultrasonic radiation(ultrasonic radiation frequency of 20kHz,28kHz and 40kHz)on the growth,breeding and biological structure on the culture water of Red Tilapia.The results were applied to the further development of the ecologically controllable intensive aquiculture technique of Red Tilapia.This paper analyzed and discussed a series of indicators of Red Tilapia such as growth conditions,survival,digestibility,feed coefficient,survival activity index(SAI)of Red Tilapia larval,the changes of zooplankton and phytoplankton.And it aimed to explore the application of ultrasonic technology in aquaculture and breeding of Red Tilapia.The results as follows:1.Comparing different frequencies of ultrasonic radiation on the growth and development of Red Tilapia larval(body weight was 0.23 ± 0.05g).The results showed that,in frequency 20 kHz the Red Tilapia larvae had the highest relative weight gain rate,was 108.80 ± 4.09g,specific growth rate was 2.45 ± 0.70%·d-1 and the apparent digestibility of protein matter was 90.60 ± 1.26%.In frequency 28 kHz,the Red Tilapia larvae attained the highest apparent digestibility of dry matter was 69.58 ± 1.94%.In which the test groups of 20 kHz and 28 kHz had no significant difference(P>0.05);The test groups of 40 kHz had the lowest relative increase rate in relative weight gain rate,specific growth rate and digestibility,but had the maximum feed coefficient,and were significant different with other groups(P<0.05).The research showed that low-frequency of ultrasonic radiation helps the growth of the Red Tilapia,while high-frequency of ultrasonic radiation inhibite their growth.2.Comparing with different frequencies of ultrasonic radiation on Red Tilapia breeding process and vitality effect on offspring larval fish.The results displayed,the incubation time of 40 kHz were shortest about 54.70 ± 2.55h,the hatching rate was also the highest about 85.62 ± 2.90%.In frequency 20 kHz,the SAI of larval fish were the highest about 34.40 ± 0.84,but it was in contrast in frequency 40 kHz.The studies showed that of ultrasonic irradiation can reduce Red Tilapia eggs’ hatching time and improved the hatching rate.With the increasing frequency(Range of 0-40 kHz),ultrasonic irradiation can enhanced the its effects.The low-frequency of ultrasonic irradiation helped to improve vitality of Red Tilapia larval,but high-frequency of ultrasonic irradiation has the opposite effect.3.Comparing how different frequencies of ultrasonic radiation effect on the biological structures of Red Tilapia aquaculture environment.Results showed that,ultrasonic radiation effects on algae was bidirectional.In frequency 20 kHz,it had the highest content of algae,but it was the lowest in frequency 40 kHz.Thus it can be seen,low-frequency of ultrasonic irradiation was beneficial to algae’s growth,but high-frequency was inhibited.Effects of 20 kHz ultrasonic radiation on zooplankton was not significant,when above 28 kHz ultrasonic radiation inhibited zooplankton,with the increasing of frequency inhibition was enhanced.4.Ecologically controllable intensive aquiculture technique of Red Tilapia.In the test,the maximum SAI of the Red Tilapia larvae was chosen,the average body weight were 3.39 ± 0.25g,ultrasonic radiation frequency was 20 kHz,aquiculture cycle was 60d.The results showed that the survival rate of Red Tilapia larvae was 98.20 ±0.84%,the specific growth rate was 1.74 ± 0.05%d-1,feed coefficient was 1.37 ± 0.04,water pH between 6.9-7.8,the concentration of ammonia nitrogen between 0.2-2.2mg·L-1 and nitrite concentration between 0.07-0.56mg·L-1.The trials achieved fairly good aquaculture results,that throughout aquaculture had no exchanging water,no drugs,no deterioration of water quality caused by breeding,nor disease situation.