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What it is
A crab and shrimp fly is a small bundle of feathers, fur, and synthetic fiber tied to look like a crustacean scuttling along the bottom of a saltwater flat. These are the bread-and-butter flies of flats sight-fishing — the patterns you tie on when you are poling a clear, shallow flat looking for tailing or cruising fish, and the ones that put bonefish, permit, and redfish in the net more than anything else.
Here is the thing to understand up front: bonefish, permit, and reds eat crustaceans. They nose down into the sand and grass and root out shrimp, crabs, and worms. A baitfish fly imitates something that swims and flees; a crustacean fly imitates something that hides, settles, and tries to bury itself. That difference changes everything about how you fish it. You are not pulling this fly away from the fish — you are putting it down in the fish’s path and letting it look helpless.
This is an advanced game, and it is honest to say so. The casting has to be accurate, often into wind, and the presentation is all about timing and restraint. But the patterns themselves are simple, and the payoff — watching a permit tip down on a fly you placed perfectly — is one of the best moments in all of fishing.
How to fish it
The whole sequence is built around sight-fishing, so it starts with your eyes, not your rod.
Spot the fish, then lead it. You cast to where the fish is going, not where it is. A fly landing on a bonefish’s head sends it bolting. Lead a cruising fish by several feet so the fly is already settled and waiting when the fish arrives. MidCurrent recommends presenting the fly five to forty feet ahead of the fish depending on depth and how spooky it is, then waiting.
Let it sink to the bottom. This is the part beginners skip. A crustacean lives on the bottom. After your fly lands, let it drop all the way down in the fish’s path. The take very often comes as the fly is falling or sitting still — watch the fish, not the line.
Barely move it. For permit especially, the rule is simple: you do not strip a crab away from a permit. When the fish closes in, you give the fly the smallest possible twitch — just enough to puff up a little sand or hop the crab a half inch — and then you let it drop again and sit. Crawl and drop. Twitch and drop. If the fish tips down on it, you wait until you feel weight before you strip-set. Stripping a crab steadily across the bottom is the single most common way to blow a permit shot.
Shrimp patterns get a little more life. A shrimp darts when it flees, so shrimp flies like the Crazy Charlie and Gotcha can take short, light strips — an inch or two at a time with pauses between — to imitate that quick, nervous escape. Orvis puts it plainly: crabs and shrimp are best imitated with short strips and a pause in between. Even here, “more life” means inches, not feet.
When to use it
Reach for a crustacean fly whenever you are sight-fishing skinny salt water and the target eats off the bottom.
Tailing fish. A bonefish or redfish standing on its nose in inches of water, tail flagging in the air, is feeding on crustaceans right now. This is the textbook crab-and-shrimp-fly situation. Lead it, let the fly settle, give one tiny twitch.
Permit on the flats. Permit are the reason crab flies exist in their modern form. Whether they are tailing on a back-reef flat, riding a stingray, or cruising a grass edge, a well-placed crab dropped in their path is the play.
Redfish and snook in the backcountry. Reds rooting along an oyster bar or a marsh edge and snook prowling shallow mangrove shorelines will both take crab and shrimp patterns fished slow and low.
Sheepshead, seatrout, and tripletail. These are bonus crustacean-eaters — sheepshead in particular are committed crab and shrimp feeders, and a slow-sunk fly near structure can draw them.
Match the weight of the fly to the depth and bottom. The trick is controlling how fast the fly sinks: bead-chain eyes give a slow, soft drop for skinny water where lead would spook fish or snag grass, while heavier lead (dumbbell) eyes get the fly down fast in two to four feet or in current. MidCurrent’s depth rule is a good default — bead-chain Charlies and Gotchas in deeper water, unweighted or barely weighted shrimp and crabs in the shallows. And on grassy bottom, a fly with a mono weed-guard lets you crawl it through turtle grass without fouling on every strip.
Patterns worth knowing
- Crazy Charlie — the original bonefish shrimp fly; bead-chain eyes, a flashy body, rides hook-point up. The benchmark.
- Gotcha — arguably the most successful bonefish pattern ever tied (Tail Fly Fishing Magazine calls it exactly that); a sparse shrimp imitation with a pink “egg sac” head.
- Bonefish Bitters — a compact, lightly weighted crab/shrimp pattern that lands soft for shallow, spooky fish.
- Merkin Crab — the pattern that cracked the permit code; a flat, fast-sinking crab that drops and crawls.
- Del Brown’s Permit Fly (the “Merkin’s” close cousin) — a yarn-bodied crab that remains a permit standard worldwide.
- EP Crab — a synthetic-fiber crab with heavy dumbbell eyes to reach the bottom quickly for permit and reds.
- Kwan — a buggy, do-it-all redfish crustacean fly for marsh and grass flats.
- Spawning Shrimp — a fuller shrimp profile that works for both bonefish and, in larger sizes, permit.
Brands worth knowing
Umpqua ties the standards — Crazy Charlie, Gotcha, Merkin, and more — in consistent, durable commercial versions, and they are the most widely stocked flats flies you will find.
Orvis carries a deep, well-curated bonefish-and-permit selection, including weighted EP-style crabs and proven shrimp patterns sorted by depth and bottom color.
EP Flies (Enrico Puglisi) makes the synthetic crab and shrimp patterns that many permit anglers swear by, with the heavy eyes needed to get down fast.
Rainy’s produces a broad line of flats and crustacean patterns at a fair price — a good way to stock a box without breaking the bank.
RIO is worth a mention on the leader side: a quality tapered flats leader turns these light flies over accurately into wind, which is half the battle in this game.