quick question

I recently found some nudibranches eating a zoa frag in my tank by shinning a flashlight in there at night. I had no idea I had them in my tank and it has been a month or so since I bought the zoas.. Though they were probably eating all day I couldn't see them till the lights were out and polyps closed since they retain the color of what they eat and they have a zoa-like body.

Although I am new to the hobby just wanted to say maybe check it out at night. Though its probably something else with the color changing and such. I didn't notice that in mine. But I'm no expert.

 

hey man if all is not well today when the lights come on snap a pic and im sure we can figure it out and get them back to normal in no time.