For the past few days I've noticed that my year old goldfish has slowed to a virtual stop.

It only seems to move about very infrequently, generally only at feeding time. Other than that, it would spend the majority of its time lying at the bottom of the tank, hiding behind one of the plants of ornaments.

It tend to be lying with a lean to its left side, almost sideways.

About a month ago, its little fishy friend died - and we've not replaced it.

Could it be that he/she's lonely ?

Thanks