It would be interesting to know different experiences with filamentous algae control with different stocking rates of Tilapia. It would also be important to know if the pond is fertilized and how heavy the bloom is, as well as the species of Tilapia and when the stocking occurred.
In early June of '05, I stocked large T. nilotica (average about a pound)at a rate of 13 lb/acre. The pond was heavily fertilized, had a good phytoplankton bloom (visibility to about 18" using the "Auburn Arm Test"), and had very large mats of f.a. at the time of stocking. The f.a. was reduced by about 90% at the surface, but never entirely disappeared, and a pretty thick bottom mat remained.
In late April of '06, I stocked T. nilotica of the same size at a rate of 13.5 lb./acre. Fertilization and phytoplankton bloom were as the year before, but the f.a. had just begun to form fairly small mats. The pond was quickly completely cleared of surface f.a. except in very shallow areas that the larger Tilapia couldn't enter, and it stayed clear. There was moderate growth of bottom mats, not nearly as heavy as the year before. For the first summer ever, I didn�t once have to pull off stinking masses of algae that wrapped my trolling motor prop in shallow water.
I suspect that stocking time is an important variable in suppressing f.a. growth. I now hector my fish supplier to make me and my neighbors first on his Tilapia list, and have concluded that a really irritating whine is the most valuable factor in good f.a. control with Tilapia, but what if he quits taking my calls?
Lou
