Why is my fish not moving very much?
If fish are experiencing acute stress (i.e., gasping up at the surface, lying on the bottom and not moving, or darting around the aquarium), you can be pretty sure that the water has been poisoned in some way. When fish show that much stress, get them into better water conditions immediately.
Why is my fish hiding and not moving?
Environmental Changes – Anything that alters a fish’s environment can spook the fish into hiding. This can include sudden water changes, temperature shifts, pH changes or chemical imbalances. As the tank stabilizes at the optimum environmental conditions, the fish should lose their shyness and stop hiding as much.