: a walk through the archaeology of Castle Bytham : fish
Along the floor of the valley lies an extensive and exceptionally
well preserved system of earthworks. The most obvious to the walker
is the rectangular hollow with a raised central platform in the field
to the left known as the "Fish Stew". The system
continues downstream with a long kidney shaped embankment which now
encloses the modern cricket field.
These earthworks represent an extremely well preserved example of
an extensive fish rearing system and are protected as a Scheduled
Ancient Monument. Such earthworks are notoriously difficult to date
as they have usually been remodelled over many years as practices
and demands changed, although they are very likely to have a medieval
origin associated with the nearby castle. The earliest possible reference
to these pools is from the 1316 record of Margaret de Colvile's widow's
portion and dowry, which included a Magnum Vivarium (Great
In their present formation the complex has been compared to the modern
'Dewbish System' for breeding carp. The fish would be spawned in the
'Fish Stew' where the raised central area would create an area of
warm water to facilitate this. The fry would then be moved through
a series of sluices into a shallow nursery pond where they would feed
on algae, the growth of which would be encouraged by the dumping of
manure and compost into the pond. Finally the growing fish would be
transferred to the main lake (where the cricket pitch is) before harvesting.
The entire process would take place on an annual cycle with the winter
set aside for maintenance of the ponds, which would need to be cleaned
and lined with clay to ensure a watertight seal.
Fish farming was an important source of revenue for the landed classes
in early medieval England and fishpond complexes can be found around
many medieval manors, abbeys and castles. Fish can be easily salted
and stored, making them an excellent food source and well worth the
effort involved in farming them. Land based livestock would normally
be slaughtered before winter as feed stocks dwindled, so by the end
of the winter fish would become an increasingly important source of
The high point of medieval fish farming is thought to have been the
12th century. An earlier date for the fish farm than 1316 may be implied
by the record used by John Wild in 1871 when he stated that after
subduing the 1221 rebellion King Henry, "learnt that the
Bytham rebels had a quantity of salt fish stored in St Leonards Priory
... [and] ordered the bailiffs of Stamford to seize, and place in
safe custody, till he gave them further orders about it"
The system at Castle Bytham is likely to have produced a quantity
of fish in excess of the Castle's own needs and so any surplus may
well have been stored close to a major market such as Stamford where
it could easily be traded.
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The Trust is supported by County
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The text shown on this page has been reproduced from a booklet written
by Dan Ratcliffe, from the Heritage
Trust of Lincolnshire, to accompany a walk around the village
of Castle Bytham which he led as part of the Midsummer
Fair in June 2004.
We are grateful for their permission to reproduce the document on