Casters
Bait · Last reviewed 2026-08-10
The pupal stage of the maggot — a bait that sinks rather than floats, has no wriggle and outfishes maggots for better fish more often than most anglers expect.
Safety
Biosecurity and disease transfer — Minor injury
Bait containers and boxes moved between waters carry water and organic material even when the bait itself is terrestrial.
What reduces it: Clean and dry bait boxes between waters. Do not introduce large quantities of surplus bait as a means of disposal.
Precautions that always apply here
- Check, clean and dry your kit between different waters — the published guidance is 48 hours’ drying, in sunlight where possible, because a number of invasive species survive over two weeks in damp conditions. Nets, boots and wet mats move invasive species and disease more effectively than anything else anglers do.
A caster is a maggot that has pupated. Left to develop, a maggot hardens into a barrel-shaped pupa which darkens from pale cream through orange to deep red-brown over a few days, and the resulting bait behaves completely differently from the maggot it came from.
The key difference is buoyancy, and it is a moving target. A fresh caster sinks. As it develops, gas accumulates inside and it eventually floats — and a floating caster is a dead bait as far as most bottom-feeding fish are concerned. Managing that is the whole craft: casters are kept cold and in water to slow development, and the ones that float are separated off before fishing.
What makes them worth the trouble is selectivity. Casters are widely reckoned to sort out better fish than maggots, particularly roach, bream, chub and tench, and they stay on a hook far better than a maggot in a current. They also produce almost no small-fish nuisance compared with maggots, which is a large part of their reputation among match anglers.
They are the classic example of a bait that requires management rather than merely purchase, and of practitioner knowledge that no scientific source addresses at all.
- What it actually is
- The pupal stage of blowfly larvae, chiefly Calliphora and Lucilia species — the same insects sold as maggots one stage earlier in development.
- How long it keeps
- Two to four days in cold water in good condition, after which an increasing proportion float and the bait becomes progressively less useful. Fresh sinking casters are the working bait; floaters are separated off and can be used deliberately as a surface or over-depth presentation. The development is continuous, so casters are bought or turned for a session rather than kept.
What it is
A hard-shelled barrel-shaped pupa, pale cream when freshly turned and darkening through orange to deep red-brown over several days. Fresh casters sink; as internal gas develops they become buoyant and eventually float. The shell is tough enough to stay on a hook well, and the contents are soft and release scent when the shell is nicked.
Finding and obtaining it
Bought from tackle shops, or produced at home by allowing maggots to turn — which is cheaper, gives control over freshness, and is how serious users obtain them. Turning maggots requires keeping them warm enough to pupate and then arresting development at the right point, which is the skill involved.
Keeping and storing it
Cold, and in water. Casters are kept in a sealed bag or tub of water in a refrigerator, which excludes air and slows development, and this is the standard method rather than a trick. Kept dry and warm they continue to develop and float within a day. Change the water daily. Casters are the most storage-sensitive common freshwater bait.
Keeping it alive
Casters are a dormant stage rather than an active animal, and keeping them viable means arresting development rather than sustaining activity: cold, in water, air excluded, water changed daily. Left warm they will hatch into flies, which is the practical failure and the reason the fridge method exists.
Preparing it
Separate floaters from sinkers by tipping the casters into water and skimming off anything that rises — this is done at the start of a session and again during it. Keep the sinking casters damp and cool in a bait box out of the sun. Dark casters are older than pale ones and closer to floating.
Using it
Hooked once through the blunt end with the hook point buried inside the shell, or side-hooked for a more natural fall. A nicked caster releases scent and is used deliberately. Casters are fished singly on small hooks for shy fish and in multiples for larger ones, and are frequently combined with a maggot on the same hook. They also work as loose feed, where they sink faster than maggots and hold fish lower in the water.
Disposing of what is left
Do not tip unused casters into the water at the end of a session in quantity — surplus bait left on the bottom is loose feed nobody is fishing over. Take them home and refrigerate for the next session, or dispose of them in household waste. Never introduce large quantities of any bait as a means of disposal.
Biosecurity
A terrestrial insect stage rather than an aquatic organism, so the transfer risk is low, but the general rule holds: do not move bait between waters as a habit, and clean and dry bait containers between trips.
Why casters are kept in water, and what is actually happening inside the shell
The instruction to keep casters in cold water sounds like a quirk of tradition and is in fact a direct intervention in an insect's development. Understanding what is happening inside the shell explains every part of the handling.
A CASTER IS A LIVE PUPA MIDWAY THROUGH METAMORPHOSIS. It is not a preserved bait or a dead item; it is a blowfly reorganising itself into an adult, and it is on a clock that runs on temperature. Everything about caster care is an attempt to slow that clock without stopping the animal's usefulness.
THE FLOATING IS A GAS PROBLEM AND IT IS THE WHOLE ISSUE. As the pupa develops, gas accumulates inside the case, and the caster's density falls. A fresh caster sinks; a developing one becomes neutrally buoyant and then floats. Since almost all caster fishing depends on the bait behaving like the loose feed around it, a floating caster on the hook over sinking feed is presenting wrongly — which is why the sink test is done at the start of a session and repeated during it.
WATER EXCLUDES AIR AND COLD SLOWS DEVELOPMENT, and those are the two levers. Immersion limits the oxygen available and suppresses the internal gas accumulation; refrigeration slows the metabolism driving it. Doing both is what buys the few days of usable life, and doing neither produces floaters within a day.
WHICH IS WHY THE WATER IS CHANGED DAILY. Casters in stale water foul it, and fouled water accelerates deterioration and smells. A daily change is maintenance of the storage medium rather than of the bait.
COLOUR IS A CLOCK YOU CAN READ. Pale cream casters are freshly turned; the progression through orange to deep red-brown tracks development, so colour tells you how close a batch is to floating. That is genuinely useful when buying: dark casters are near the end of their working life whatever the seller says.
AND FLOATERS ARE NOT WASTE. Skimmed floaters are a deliberate bait in their own right — for surface presentations and for fishing over-depth where a buoyant hook bait sits above bottom debris. Separating them is sorting, not discarding.
THE PRACTICAL CONCLUSION IS THAT CASTERS ARE BOUGHT OR TURNED FOR A SESSION rather than kept, and anybody planning around a week-old batch is planning around a bait that will be floating by then.
Practitioner consensus
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
- Coarse Fishing — A. & C. Black, 1912 (Specialist angling publication)Relied on for: Established coarse angling bait practice, preparation and care.States this directlyCitation checked — the work exists and is described correctly
- Freshwater Fishing — Macdonald & Jane's, 1975 (Specialist angling publication)Relied on for: Freshwater angling practice, including the obtaining, keeping and presentation of natural baits.States this directlyCitation checked — the work exists and is described correctly
Where to go next
Fish it catches
What these connections rest on (1)
Practitioner consensus — 1 connection
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Roach
A practitioner claim about relative selectivity, labelled as convention because no controlled comparison supports it.
- Coarse Fishing — A. & C. Black, 1912 (Specialist angling publication)Relied on for: Early practitioner treatment of caster use and its selectivity in British coarse fishing.Citation checked — the work exists and is described correctly
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary practitioner treatment of casters as a bait that sorts better fish.Citation checked — the work exists and is described correctly
Understanding it
What these connections rest on (1)
Scientific evidence — 1 connection
Supported by peer-reviewed research or fisheries science. The sources are listed and can be checked.
Why bait dies quickly
The bait record is where the failure is experienced.
- Cefas science, advice and data on marine and freshwater environments — Centre for Environment, Fisheries and Aquaculture Science (Government fisheries body)Relied on for: The relationship between water temperature, dissolved oxygen capacity and metabolic demand in aquatic organisms.States this directlyCitation checked — the work exists and is described correctly
Instead of this
What these connections rest on (1)
Practitioner consensus — 1 connection
Widely and independently recommended by experienced anglers and specialist sources. This is real angling knowledge, not proof: controlled evidence for it is limited, and FishingHQ records it as convention rather than as a demonstrated effect.
Maggots
A practitioner comparison between two forms of the same bait organism.
- Coarse Fishing — A. & C. Black, 1912 (Specialist angling publication)Relied on for: Early practitioner treatment of the relationship between maggots and casters.Citation checked — the work exists and is described correctly
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary practitioner treatment of when casters are preferred to maggots.Citation checked — the work exists and is described correctly
More bait
Not related to this page — just the rest of the section, because this record connects to very little and a short page should still lead somewhere.
Check the rules before you fish
Fishing laws, bylaws, access rules, seasons, bait restrictions and permitted methods vary by location and can change. Check the current rules from the relevant authority and the water you intend to fish before fishing.
Check with:
- Current national or regional law for where you are fishing
- Current local bylaws
- The relevant fisheries authority
- The landowner, club or fishery whose water it is
- Any restrictions specific to the species or the method you intend to use
Sources for this page
- Coarse Fishing — A. & C. Black, 1912 (Specialist angling publication)Relied on for: Early practitioner treatment of caster preparation and use in British coarse fishing.FishingHQ's interpretation of what it saysCitation checked — the work exists and is described correctly
- Angling Times — Bauer Media (Specialist angling publication)Relied on for: Contemporary practitioner treatment of caster storage in water, floater separation and their selectivity for better fish.FishingHQ's interpretation of what it saysCitation checked — the work exists and is described correctly
How FishingHQ labels evidence is explained in the evidence policy.