Lost my dwarf gourami. What's going on here?

I've got one of those thermometers that you stick on the side of the tank and honestly I don't know how to read the thing. It came with the kit and there were no instructions that I could find. 76F is in blue and 78F is sort of a cream color. All the rest is too dark to read. So I'm guessing maybe the temp is 77F?

You're right. I don't sit and watch the tank 24/7 but I am a stay at home mom and I do go watch the tank tank several times a day as my almost 9 month old loves to watch the fishies. I have never observed the barbs pestering the gourami except for the first day or two after I put them in.
 
AquariaCentral.com