When you say catfish, what kind? Channel don't disturb the bottom much when foraging, where Bullheads and common carp will muddy any waters.
Do you have exposed clay above the waterline? If so, that will need to be vegitated before anything will clear the water.
Have you done a jar test? Put some pond water in a clear jar and let it sit undisturbed for several days. If the water clears something mechanical is muddying the water (fish, wave action, cattle, etc) If nothing, or VERY little settles to the bottom, other means will be required to clear the suspended solids. (alum, barley straw, hay, polymers, lime, gypsum, etc)
