Green bta turning brown

[mochajungle]

My bta started to retract its tentacles and is turnin slightly brown on the sides
I’ve had him for about 3 weeks and when I first got him he was doing great until the tomato clown started hosting him

I don’t think it’s got to do with water quality or lighting cause everything else seems happy and my other men I doing great
Tanks been up for about 5

months

 

[Hemmdog]

What kind of light is it. What have you been feeding the nem.