A shoreline choked with weeds does exactly that; excessive plant life in shallow water can deplete oxygen in the water at night -- when plants consume, rather than release oxygen -- and suffocate fish. Plant cover can also limit your beach or dock access, so it is in your interest to remove weeds from your shoreline.
Things You'll Need
Put on waders and gloves.
Dig up in-ground weeds, like cattails, with a shovel. Pry them up and out of the ground, getting as much of the root as possible. The key is to remove the roots, otherwise they keep coming back. Remove the plants from the water. Decomposing plants in the water can release nutrients that encourage plant growth, and can further deplete oxygen.
Remove long stringy water weeds that float on the surface, or just below, skimming them off with a rake. If the weeds are too far out to reach then drill a hole in the handle and tie a rope to it and then you can throw it out and drag it in. This technique is a lot of work but is effective. This technique also works on lily pads.
Apply aquacide when mechanical methods fail or are impractical, such as when dealing with algae. Search for the least toxic chemical listed as effective for the particular weeds you are dealing with; Diquat, 2,4-D, fluroidone and glyphosate are among the less toxic water herbicides, according to Virginia Cooperative Extension. The extension service also recommends using herbicides in early spring when weeds are smaller and only treating small areas at a time to allow fish to move to untreated water.