Fish require structure for safety as well as for feeding and reproduction. Structure can be natural to the pond or man made.
When adding structure, make sure to incorporate all the depths and contours as well. Provide structure in several depth levels and contour areas throughout the pond and not all just in the shallow or just in the deeper portions.
Common Natural Structure
Aquatic Plants - Plants often serve as important structure for both bait fish and predator fish. You need to strike a balance with plants though, as they can quickly take over a pond or lake. Dense patches of plants with distinct weed edges, along with other areas of sparse vegetation is best. Virtually all fish species will relate to some sort of weed cover in ponds.
Rocks & Boulders - Large rocks can work as great structure elements for fish by themselves, or piled to form "sunken islands". The crevices are perfect places for the production of some forage such as crawfish and insect larvae as well. This will draw in fish to feed. Smallmouth Bass and Walleye often relate to rocky structure for feeding and reproduction.
Downed Timber - Downed trees and brush piles are great structure elements for fish, especially early on when the small branches are still intact. This provides excellent safety as well as good fishing opportunities. Panfish, Walleye, and Bass all use downed timber. Larger predator fish often cruise these areas looking for easy meals.
Common Man Made Structure
Fish Cribs - Often built on the ice during winter in the north, these can consist of logs tethered together in a "log cabin" arrangement or more randomly placed. These provide similar benefit to downed timber, but since you are placing them, you can strategically stage them in deeper water areas. Hardwood trees or species such as Cedar hold up longer in the water than other softwood species.
Vertical Cribs - An easy to make and effective structure is a vertical crib, or simply, a small tree or other vertical structure cemented into a bucket. The bucket serves as a weight and keeps the structure vertical. Christmas trees are often used for this, but will degrade overtime in the water. This structure is great for Crappie or other species that like to suspend in the water column.
PVC Cribs - Constructed in many configurations, commercially or homemade PVC structure can serve well as structure, and the main advantage is it will hold up much longer in the water than wood structure and will not degrade. It also provides much less chance of getting snags as you are fishing.
Barrels- Plastic or metal barrels are often used for catfish structure. Catfish will use these areas for laying eggs as well as for rest. If you are into "noodling" for catfish, this also provides for pinpoint areas to look. Just watch out for those snapping turtles.
Docks - Docks or any other structure that provides vertical areas (pilings) and overhead shade are great structure points for Bass and Panfish. Especially in the south, the shade can be of great help for the fish.
Unusual Structure - Man made structure can virtually be made of anything. If building a new pond, one unique form of structure is junker car bodies. These actually provide very good structure for many species. Make sure you only use the metal shell and remove all liquids, batteries, upholstery, etc. from the shell before submerging it.
Kasco Marine, Inc., 800 Deere Rd., Prescott, WI 54021