This section is from the book "Frank Forrester's Fishermens' Guide", by Frank Forrester.
This is an odd-looking fish, his belly being on one side and his back on the other. He is shaped something like the sun-fish or pumpkin seed, and on the edges, where the belly and back of an ordinary fish would naturally be, he has continuous fins from neck to tail. The back is of a dark color, both eyes being on that side, and guaged to look upwards at an angle about one-fifth forward from perpendicular; and his belly is usually white. The size of the flounder varies from five to fifteen, and sometimes to twenty-four inches in length, the breadth being about one-half the length. Their feeding ground is the soft mud of the bottom, near to bridge spiles, docks, and other bottom incumbrances, and they are sometimes found on bass grounds. They feed on the spawn of fishes, and on muscles and insects.
The time for fishing the flounder is the spring and fall months. In the summer he may be taken, but his flesh is soft and unwholesome. He will bite at almost anything used in salt water for fish bait, and in fishing him you may use any kind of tackle. A small hook is however necessary - No. 8 being the usual size. Flounders are an excellent pan fish; but they should be cooked as soon as possible after being taken. They are very plentiful on the shores of Long Island Sound, in New York Bay, and in the inlets of New Jersey. The Boston market is abundantly supplied with them from the numerous fishing grounds of that neighborhood.