I know anglers who pride themselves on landing 2lb-4lb trout on 4x-6X mono tippet with a fly rod. (That’s 4.3lb – 2.1lb breaking strength, by industry norms.) They probably wouldn't consider themselves ultralight anglers. Since not everyone is proficient, or even interested in fly fishing, what constitutes an "ultralight angler" with a spinning rod? Just for the sake of it, I'm going to say 4lb test or less, because that's what I have used for the last twenty five years.
I've owned a lot of spinning rods in my lifetime, but I guess I really started taking ultralight spinning seriously in the early 1990s. During the last five years of the my USAF career, I was stationed in Alabama and in Washington, D.C. Bass, hybrid striped bass, pan fish, and the occasional foray into Maryland trout waters gave me ample opportunity to work on my ultralight fishing skills. I was also building my own rods at the time, so I was in control (to some extent) of my ultralight solution. The rod: a 5' slow, medium, or fast-action spinning rod. Of the dozen or so I've built over the years, I've always used G. Loomis IM6, GL3, or IMX blanks (it’s sad they don’t offer their blanks anymore). The reel: when Shimano released the first Stradic reels, I had my ultralight reel. The line: Berkley® FireLine® first hit the market in 1998. For years I'd used Ande Tournament mono, but when FireLine® came out, my ultralight solution was complete.
G. Loomis still makes the SR6010 IMX and GL3 rods, and several other manufacturers have 5' ultralights. However, factory rods all have standard reel seats. I much prefer Tennessee handles with graphite rings. Although most of my early builds had cork grips I've also used graphite tubes, and my latest is a Kevlar® tube. Tennessee handles are lighter, and provide ever so much more sensitivity at the reel that anything the lure touches is felt in the handle. Factory rods generally had only four guides. My latest builds used the best guides available at the time, and I added a fifth guide for smoother casting and reduce line stress during retrieves. I built a few rods with single-foot guides, but settled on double foot as more durable for the long term. Although I really loved my slow IM6 ultralight, the GL3 and IMX versions are far more accurate when casting long distances.
I settled on the Shimano “Stradic 1000” with a 6:1 retrieve ratio as the ideal ultralight reel. Not only is the Stradic a high quality reel that will take a lot of wear and tear, the 6:1 ratio was exactly what was required for fishing inline spinners in fast water. Additionally, the Stradics have a reliable drag system that is essential for ultralight fishing. I've owned and recycled (through Ebay) at least a dozen Stradic 1000s over the years. Currently I'm using three Stradic “CI4” reels, Shimano's carbon fiber model. All reels take some abuse, and Shimano has proven over the years to have a good service program that will extend the life of any hard-used reel. Mine get a lot of work every season, and I don’t hesitate to have them serviced over the winter.
Before there was FireLine®, monofilament was the only real choice for ultralight fishing. The Ande Tournament line was the best around, but as with all mono, it twisted, kinked and deteriorated with use. When FireLine® first came out in 1998, it was expensive and it still is. However, 4lb FireLine® will outperform (in my opinion) any 4lb test mono or flouro line on the market, including its close cousin NanoFil®. It doesn't twist, doesn't kink, rarely breaks at the knot, and will not deteriorate on the reel. It will cast a #2 in-line spinner (1/6-3/16 oz) significantly farther with greater accuracy than mono. I tie all my lures directly to the line with a Palomar knot, forgoing swivels that just kill the action of any in-line spinner. A day’s fishing an in-line spinner will put a lot of twist in mono, but none in FireLine®. Because it is "no-stretch", everything the lure encounters, is felt at the rod handle. "No stretch" even has advantages when you've tossed a lure a bit too far into the bank, as a little jiggling will often bounce the lure loose. Although 125yds for $18 seems like a lot of money, those 125yds will outperform mono and remain functional on the reel for years.
Today, my ultralight fishing is almost universally with #2 Mepps and Blue Fox Vibrax inline spinners in fast rivers for western trout, but my setup handles other lures just as well. 1.5” and 2” Rapala “Shad Raps” were killer lures for walleye, smallmouth and pike in Northern Minnesota. Heddon “Tiny Torpedos” sucked up a lot of smallmouth in Maryland and Virginia. When the crappie were biting, small crappie jigs could finesse fish out of tight cover in Alabama. And it was a real blast to rocket out #2 Silver Mepps into trashing schools of hybrid striped bass and white bass on central Alabama lakes. Even when I needed a few catfish for the vegetable garden, a big pink worm and a few spit shot on the ultralight was deadly in the right places. The largest I ever hooked and landed on the 4lb FireLine® was a 15lb blue cat.
I was fishing 5' ultralights well before I had my first kayak, but once I found myself spending more time in 12' plastic boats, the 5' rods fit right in. Although I’ll occasionally use a rod holder in my Native “Ultimate Tegris”, the 5’ rod tucks nicely under the bow with the reel resting on the seat straps, out of the way. We could have an endless debate on ideal rod lengths, the best reels, and of course the pros and cons of the wide variety of fishing line on the market. But I’m beyond that. For the last twenty-some years my ultralight solution has served me well, and put thousands of fish of multiple species, both big and small, on the books.