What are the causes of mortality? Is all mortality in catfishes natural? This and many other questions are often asked by catfish farmers, most especially new farmers who are willing to minimize loss due to mortality. Times without number, catfish farmers have been sent out of business due to uncontrolled mortality rates. Some six years ago, I was seriously affected by severe mortality in my catfish farm. I almost lost my confidence in the business. I began to search for basic causes of mortality in catfishes and how to control mortality if there is any solution to this problem. In this article, I shall be examining various causes of catfish mortality. This I believe will make farmers to reduce the effect of mortality once the cause is known. For easy reading, causes of catfish mortality have been grouped into five categories. Each category will be discussed briefly to give sufficient information on this matter.