One of our most troublesome aquatic weeds is filamentous algae. It starts early in the season and will hang around pond and lake shores all season long. Control options include physically pulling it out, using grass carp, aquatic dyes, and copper based aquatic herbicides. I recently learned about another option for control using tilapia.
Oreochromis aureus, blue tilapia, have a strong herbivorous tendency, preferring aquatic plants and algae when readily available. Because of this trait, blue tilapia are often a top choice for those wishing to stock tilapia in earth basin ponds for controlling nuisance aquatic plants.
According to our state wildlife specialists, if you put enough into a pond they will eat all the algae. Depending on which species you buy but they all die when the water gets close to 55 degrees F. Blue tilapia are the most cold tolerant and need to be stocked as fish larger than 6 inches and ready to spawn for the most success. They will spawn throughout the summer. Somewhere between 5 - 10 pounds per acre. This intensity may reduce other species fish growth due to limited food chain development. They seem to really like filamentous algae and there are no restrictions in Kansas for tilapia. One of the drawbacks to tilapia may be if you don't have enough predators and scavengers, you could end up with a horrible smelling mess in the fall as they die out.
Consider tying some blue tilapia for annual algae control and let me know how it works.