Updated July 24, 2026 · By Drillstrings Technical Team
Fishing is the downhole intervention work of recovering a fish — any object lost or stuck in the wellbore that blocks further operations. That fish might be parted drill pipe, a dropped bit or bit cone, a packer, wireline, a lost hand tool, or metal debris (junk). Successful fishing depends on correctly identifying the fish, running the right catch and impact tools, and knowing when the economics say to stop. This primer covers the fundamentals.
What counts as a fish
Common fishing scenarios include:
- Parted or twisted-off drill string — a tensile or fatigue failure leaves pipe and BHA in the hole.
- Stuck string that cannot be freed by conventional means (see our companion guide on stuck pipe).
- Lost bits, cones and stabilizers dropped or broken off downhole.
- Wireline and slickline left in the hole after a tool string separates.
- Packers, plugs and completion hardware that must be milled or pulled.
- Junk — slips, tong dies, bit cones, hand tools and metal debris on bottom.
The first step in any fishing job is building an accurate picture of the fish: its top depth, outside and inside diameter, length, condition and orientation. This drives every subsequent tool choice.
The fishing toolkit
Catch tools
Catch tools grip the fish so it can be pulled or jarred free.
- Overshot — the workhorse external-catch tool. It slips over the fish top and grips the outside diameter using a spiral or basket grapple. Overshots are versatile and releasable.
- Spear — an internal-catch tool that engages the inside diameter of a tubular fish, used when the annular clearance is too tight for an overshot or when only the ID is accessible.
- Taper tap and die collar — thread-cutting catch tools that bite into the fish top; used when clean grapple engagement is not possible.
Impact and force tools
Simply pulling rarely frees a stuck fish. Fishing strings deliver controlled impact:
- Fishing jars — deliver a sharp hammer blow up or down when the string is stretched or set down and released, cycling repeatedly to work the fish loose.
- Accelerators / intensifiers — store energy above the jar and amplify the blow, protecting the string above from shock.
- Bumper subs — provide stroke to control spacing and deliver down-jarring impact.
- Safety joints — a deliberate weak point that lets you back off cleanly and leave the catch tool on the fish if the string must be recovered.
Cleanup and milling tools
- Junk mills and flat-bottom mills — grind up junk or dress a fish top to a catchable profile.
- Junk baskets and magnets — capture cuttings, mill debris and small metal junk.
- Washover pipe — mills over a stuck fish to free the annulus before catching it.
Our fishing tools and complementary downhole tools cover catch, impact and cleanup for standard and specialty jobs.
The fishing workflow
A disciplined fishing operation follows a repeatable sequence:
- Diagnose the fish — depth, dimensions, condition and cause of loss.
- Run an impression block or gauge if the fish top is unknown, to image its profile.
- Design the fishing BHA — catch tool, jars, accelerator, bumper sub and safety joint sized to the fish, hole and depth.
- Engage the fish — establish a positive catch, confirmed by weight indication.
- Jar and work the fish — apply controlled up/down impact within string limits.
- Recover or release — pull the fish, or back off cleanly if it will not come.
- Reassess at each unsuccessful cycle against pre-set economic limits.
Every step is documented; catch confirmation and jarring loads are logged to guide the next decision.
The economics: when to fish and when to sidetrack
Fishing is ultimately an economic decision, not a point of pride. Before a fishing job begins, set clear limits:
- Economic limit — the maximum spend (rig time plus tools) beyond which sidetracking is cheaper.
- Time limit — a number of days or attempts after which you reassess regardless of cost.
- Probability of success — a realistic, declining estimate of recovery odds.
When cumulative fishing cost approaches the cost of plugging back and drilling a sidetrack, or when recovery odds fall too low, the right call is to stop, cement a plug and drill around the fish. Many operators define a “fish-or-sidetrack” decision tree at the well-planning stage so the choice is made on data, not emotion, under pressure.
Safety and best practice
- Do not exceed string limits when jarring — tension and torque overload can create a second, worse fish.
- Keep the hole full and monitor for influx during long intervention operations; fishing is still a live well control situation.
- Use safety joints and back-off procedures so you can always recover your fishing string.
- Match tools to the fish, never the other way around — an under-gauge or wrong-catch tool wastes rig time and can damage the fish top.
Fishing tools on rental
Because fishing is intermittent and the required tools are highly specific to each fish, fishing equipment is one of the strongest cases for renting rather than owning. A well-stocked rental fleet lets you mobilize the exact overshot, grapple, jar and mill for the job — sized correctly the first time — without maintaining idle specialty tools.
If you are planning a fishing operation or facing an unexpected fish, our technical team can help you diagnose the fish and assemble the right string fast. Contact us with the fish details — depth, dimensions and how it was lost — and we will get the right tools moving.