I am helping you. If you don’t format your code, others cannot determine if its failure is simply due to an indentation error.
You have two choices, select the code and click the formatting icon </>. Alternately, put three consecutive back-quotes ``` on a separate line before the code. Then put three consecutive back-quotes on a separate line after the code.
All text-formatting in this community forum is based on markdown.
1558526196: New client connected from 192.168.1.101 as fishtank-Sonoff (c1, k10, u’adam’).
1558525821: New client connected from 192.168.1.121 as Office-Sonoff (c1, k10, u’adam’).
Here the thing, as long as the indentation and syntax are correct and even if the topic is wrong or not receiving any messages, the switch’s configuration will be recognized by Home Assistant and it will appear in the States page. I copy/pasted your fishtank configuration to my system, restarted it, and here it is in the States page:
The fact that it is not appearing in your system suggests something may be amiss with where it was defined. Do you have any other switches defined in configuration.yaml and do they appear in the States page? What other entities have you defined (that appear in the States page)?