Create a brown trout They have a single soft dorsal fin and their pelvic fins are abdominal. Size: Brown trout vary significantly in size depending on theira habitat and food availability. In streams, they typically range from 15 to 22 inches in length and weigh 1 to 5 pounds, but can grow much larger Their bodies are generally olive green to brown on top, fading to a creamy, golden-yellow on the sides and an off-white belly known for their distinctive spots. They typically have black spots along their sides, back, and dorsal fin, often surrounded by a lighter halo. They have an elongated body that tapers at both ends, a relatively slender body with a long, narrow head Their caudal fin (tail fin) is delta-shaped and not forked.