Fresh waters account for less than 1% of the total water on earth, yet nearly 40% of all living fish are found in fresh water. One reason for this is the diversity of the types of fresh water. Rivers and streams provide very different types of habitats at different elevations. They differ in flow rate, botom type, temperature, pH, dissolved oxygen content, and other chemical factors. Even lakes are quite different, ranging from deep, cold lakes to shallow, sun-warmed lakes.

Class characteristics:

• Slinder, eel-shaped body.
• 7 external gill openings.
• The notochord persists in the adult.
• The skeleton is composed of cartilage.
• There are no paired fins.
• The adult digestive system has no stomach.

One representative of the Family Petromyzontidae has been found in Arizona:

• Sea Lamprey - Petromyzon marinus - a parasitic lamprey.

Lamprey life cycle:

• Lampreys will lay their eggs in flowing water.
• When the eggs hatch, the larvae drift down-stream to an area with a soft, but not muddy, bottom.
• They dig into the bottom and form a burrow with their mouth just above the bottom.
• A good portion of the lifespan of the animal is spent in this filter-feeding larval stage known as an ammocoete. As with most larvae, they do not yet have sex organs.
• When the metamorphosis to adult occurs, the lamprey swims into the water.
• The Sea Lamprey will search for a host to feed on blood before mating.
• Some Lamprey's do not eat as an adult. They mate and die in one to three weeks.

Some lampreys need flowing water with a rocky bottom to build a nest, lay their eggs, and spawn. This limits their range to rivers and streams with this characteristic.

Class characteristics:

• The skeleton is composed of both cartilage and bone.
• Most of the fins on the body are paired.
• Most freshwater fish are covered with scales.

Trout are probably one of the most widely fished species in Arizona they can be found in many of the streams and lakes of the white mountains and the rim country. Take a look at this link for infromation on many different type of trout.

Some common bass found in Arizona are Largemouth, smallmouth and yellow bass. Some other common fish species found in the lakes are walleye, yellow perch, crappie, sunfish, channel catfish and carp. Saguaro Lake is the closest lake to the Phoenix area on the Salt River Chain and contain some of the fish previously mentioned.

Fish identification:

When using a dichotomous key to identify fish, an understanding of the basic body parts is important. There are a number of measurements on the body and head that are important.

The skulls of fish are much different than most other vertebrates. There is no large "skull". The skull is composed of many small bones that are not fused together.

Teeth can clearly be seen on the mandibles and maxillae of this fish. Its species is unknown, but it is obviously a large fish that is not native to Oklahoma.

Research Links:

• Fishing Arizona - Arizona Game & Fish
• Vertebrata - U.C. Berkeley
• Freshwater Fish - Texas Parks and Wildlife Department
• Natural History of Minnesota Fishes - University of Minnesota
• Orangethroat Darter - Illinois Natural History Survey
• Fish Key - Illinois Natural History Survey
• Angler's Guide to Fish Diseases and Parasites - University of Georgia
• Chordate Anatomy and Evolution - George Washington University