Most times some catfish farmers complain that they got to their pond and discovered that the fishes were rubbing their bodies against the wall of the pond.
Well the common cause of this is when fish are having skin disease or when their water has become too dirty. From practical experience, dirty and turbid water is usually responsible for this. Commonly, if it is due to dirty water, changing the water immediately will make the condition subside.
In the case of water get bad faster, there are three major things that may be responsible for that, one it is either the source of the water used is bad or that the fish are being overfed thus polluting and contaminating the water.
There may also be an underlying disease which is resulting in this.
Therefore in order to avoid this, it is good to be sure that the source of the water you are introducing into your pond is good. Do proper feeding and avoid over-feeding as much as possible.
However, if after changing the water, they still keep on rubbing their body against the wall, it may indicate skin disease which should make you call on your consultant for immediate treatment.