I I just got some clown loaches and they are in my tank finnished Acclimating and I noticed 1 out of 4 of them hides behind a rock I have a lot. Whereas the other 3 are swimming around the front of the tank having a great time. Also when he is at the back of the tank he sits on the gravel. If it helps my water parameters are ph 7.5. Ammonia 0ppm. Nitrite 0ppm. Nitrate 5ppm. I used a drip loop aclomation which took about an hour and a half. Please help me I am really worried about him.