[MOVED] Night sensor - turn automatic on

[stonefox]

I have an aquarium where I've made a Nightlight, with a number of blue LED diodes. View picture.

My desire is that it turns on automatically when it starts and gets dark in the evening, how can I fix it?

Are there components I can use on my plus wire which has this feature?

 

[Golden Electronics]

U can use LDR circuity