The author caught this 5-inch, 4-year-old-rainbow trout in an unnanmed tributary of the Peabody River in Green’s Grant.

WHEN I was very young, my mother told me an interesting fact about goldfish.

“A goldfish will stay small in size”, she said “when it is kept in a small bowl. Likewise, one kept in a larger bowl can grow much bigger.” I’m sure that her intention was a colorful metaphor encouraging her son to seek experience, exceed limitations and “grow” as much as I could in a great big world.

Her advice fell on deaf ears ... not because I lacked ambition or creative reasoning, but because she spoke of fish. Fascinated by fish since birth, I missed her point and instead considered the life of her goldfish ....or any fish, and wondered how they grow and which factors determine their ultimate size. Some fish never exceed one inch in their lifespan while others grow bigger than my imagination could process.

My mother’s story was a powerful one and even today, thoughts like these can keep me awake at night.

All fish (and the majority of living organisms) have evolved to make the most of their living conditions and thrive. What separates them by size, I’ve learned, are the parameters in which they exist. A fish living in a small stream simply will not grow as big as one in a large river. Just like the goldfish’s relationship to its bowl, there are limitations that keep fish from getting too big for their britches.

In contrast, there are conditions where a fish may live longer and get bigger than nature may have intended.

Many species of fish may exemplify this magical relationship and for the sake of today’s discussion let’s talk about rainbow trout. Although not native to New Hampshire, they have become an important part of our sportfishing and I catch them regularly.

Worthy of significant consideration is the fact that the rainbow may represent both the smallest and the largest fish I’ve ever caught. Because of the water chemistry in the Androscoggin River, these trout reproduce as successfully as brook trout do everywhere else.

No longer limited by acidity or its buffers, rainbow trout are found in many tributaries and make up a significant amount of the biomass within the entire watershed. This means that juvenile fish are found in the headwater streams, larger fish are found at the confluence, and some real monsters swim around in the mainstream.

Understanding this relationship allows a reflective angler to re-evaluate his or her idea of a trophy fishing experience. Trout do not often exceed 4 years old in New Hampshire and recognizing this is a good starting point. If I’m standing in the knee-deep water of a small stream, able to step from pool to pool, this 4-year-old fish might be 5-inches long. If I am fishing in fast, deep water that I can barely cast across, I may catch a 4-year-old fish that is 16 inches long, weighing 2 pounds. Finally, if I am fishing a giant river where a 4-year-old fish can migrate between large lakes, it may reach a length of 22 inches and exceed 8 pounds.

I can take equal satisfaction in catching any of these fish. They have all lived through the perils of several years and have likely reproduced, thus sustaining the population. I take pictures of every fish I catch and, while some of them would make the cover of a magazine or bragging board, some would not. For me, they are all trophies who, like goldfish in a bowl, embody the spirit and endurance that I have loved for as long as I can remember.

Adventures Afield appears in the New Hampshire Sunday News. Contact Andy Schafermeyer at troutandsalmon1@gmail.com.