I've had a blue gourami in my 36 gallon bowfront tank for about 6 months now. He's in there with 5 serpae tetras and 4 corys. He used to be really active and swim near the top or middle of the tank. But a couple weeks ago I added some java ferns and crypts and rearranged the rocks in my tank. Now he hides behind the cyrpts in the bottom back of the tank, or if he comes out he hides up in the hornwort thats floating at the top. He never used to be skittish, but now anytime I walk by the tank or go to feed the fish he darts away and hides. Any reason why he would do this all of a sudden?