What's a Zoo Cougar? Well it's probably one of 3 things: a big cat in a cage, a feisty aging cat that hunts younger males, or a killer streamer fly. Let's just say we like the last option the best. The Zoo Cougar Yellow is ferocious on big browns and other big trout, as well as bass, pike, muskies, and many other aggressive species. It's large yellow spun hair head makes a lot of noise as it pushes water aside with each strip and the flowing mottled body lends just the right look as it swims along tempting big fish to strike.