Your Kuhli Loach looks awesome! I have one just like that. He is at least 5 years old and has survived through all of my trials and tribulations.
It appears that you have two kuhlis. One with more black than the other. Nice setup. Your gravel looks a bit large, what exactly are you using as the substrate? Also, did you have to get a new light for your 12? I have a 6 and I'm thinking about setting it back up but with a new light. I had to tear it down because sheets of algae started to grow on everything and I couldn't control it. I'm talking "SHEETS".