Some of our fifth and sixth class students did research projects on some of the other freshwater fish which we found when we did the field trip.

They researched the life cycles of brown trout, freshwater eels and mayfly.

We came across some amazing facts. Did you know that a single female brown trout can lay between 400 and 2,000 eggs, that eels travel 4000 miles to breed and adult mayfly only live for a few minutes or a few days!

If you want to learn more about these incredible creatures you can read some of the projects below.

Interesting Mayfly Facts:

Mayfly can reach 0.5 to 1 inch in length.

Most species of mayfly are green-colored.

Mayfly has large, compound eyes, short, flexible antennas, elongated, narrow body, two or three long tails and two pairs of membranous wings. First pair of wings is much larger than the second pair. Wings are kept upright (above the body) when they are not in use.

Both males and females have two sets of genitals. Females have two sexual openings, while males have two penis-like organs. Males also have larger eyes than females to ease detection of mating partners during the brief breeding season.

Mayflies consume algae during the larval stage. Adults do not have functional mouths and they do not eat.

Mayflies are important source of food for the trout, bass, catfish, frogs, newts and birds.

Mayfly undergoes three developmental stages: egg, naiad (larva) and adult.

Female lays thousands of eggs on the surface of the water. They sink to the bottom and usually hatch month and a half later.

Larval stage (naiad) may last few months to 3 years and it takes place under the water. Larvae have elongated, slightly flattened, cylindrical body and robust legs covered with hairs, bristles or spines. They have gills that are used for breathing.

Adult mayflies emerge from the ponds, lakes and streams from spring to autumn (only few species hatch during the May).

Mayflies have unique, transitional stage, called subimago. Fully winged, terrestrial mayflies in the subimago phase need to undergo one last molting session to reach sexual maturity and become ready to mate.

Mayflies are best known for their extremely short lifespan. Adults live from few minutes to few days. Their only purpose is to reproduce and they die as soon as they complete this mission.

They mate, spawn and die in a single day.

Mayflies are indicators of the pollution of the water (they can survive only in the clean waters).

Mayflies are often used as models for the creation of artificial flies for fly fishing (they are used to attract trout).

Freshwater eels

Freshwater Eel


The Frshwater Eel’s body is long and slender, and seems scaleless. Actually, it has smooth, tiny scales that are embedded in the skin. A long, low dorsal fin extends over at least two-thirds of the back. It blends with the caudal fin and the anal fin, which is also long and low, on the underside. There are no pelvic fins, but the pectoral fins are well-developed. The presence of pectoral fins can be used to distinguish an Eel from a Lamprey, which has no paired fins. The head has a smallish eye. The head is long, and tapers to a small mouth. The lower jaw sticks out a little farther than the upper jaw. Eels are yellowish brown to dark-olive, and lighter underneath.


After the adult Eels spawn, they die. The larval Eels, called “leptocephali,” are ribbon like and transparent. These “glass Eels” drift  in the northward-flowing ocean currents. The transforming young Eels, called elvers, enter river estuaries when they reach the continent. The females don’t stop. They continue swimming many miles upstream, mainly at night, even to the river system’s headwaters. The trip from the spawning grounds in the ocean to the Eel’s freshwater upstream home takes about a year. The male Eels, which remain smaller than the females, stay in the lower reaches of the coastal river and in the brackish tidewater just off the river’s mouth. After remaining in fresh water for 10 to 20 years, the adult females, now called “silver Eels” because of their silvery appearance, migrate downstream in the fall on their long way back to the Sargasso Sea.

Adventures of a brown trout…and other freshwater creatures.