Gut wash, body soak, blender and heat-fixation: approaches to the effective collection, fixation and preservation of trematodes of fishes.

Advice is offered on some effective methods for collecting and preserving trematodes from fishes for taxonomy and systematics. Emphasis is placed on obtaining high-quality specimens that have reliable data and that are amenable to study by both morphological and molecular approaches. We emphasise the importance of the freshness of the host specimen, the reliability of its provenance and the labelling of the specimens. For the collecting itself, we recommend a 'gut-wash' approach for gastro-intestinal species and specific searches for atypical taxa such as didymozoids, aporocotylids, Saturnius Manter, 1969 and transversotrematids. For metacercariae, we recommend a 'blender' approach to release parasites from host tissues. For fixation, we argue in favour of heat-killing in fluid at close to boiling temperature. We recommend against flattening as a routine procedure for collecting specimens for morphology. Preservation for morphological study is best in formalin or alcohol, and alcohol works well for molecular samples. The importance of reliable labelling and the deposition of specimens in museums is emphasised.