Record #00471Nature archive
Smallest Freshwater Fish by Mature Body Length
A taxonomic study published in 2006 described a sexually mature female Paedocypris progenetica from Indonesian peat-swamp waters with a standard length of just 7.9 mm, making the species a leading contender for the smallest freshwater fish.
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Overview
Archive NoteResearchers found this miniature cypriniform fish in highly acidic blackwater peat swamps. Adults retain anatomical features normally associated with larval fish, showing extreme miniaturization and paedomorphosis.
The authors measured standard length and verified maturity by dissection or transmitted-light examination. The original paper also warns that habitat destruction threatens these specialized fish.
Record history
1 Milestones- 7.9 mmPaedocypris progeneticaCurrent Record
Sources
Evidence & ReferencesVerification basis and limitations
Evidence-backedCredible sources support core facts; the comparison scope or corroboration remains incomplete.
Basis: corroborating reliable secondary materials
The original 2006 research directly documents a fully mature 7.9 mm female and its small-fish candidacy. The figure is standard length, not total length. Publication in 2006 is not the origin date of a natural record, and other smallest-fish definitions and candidates remain; developing is retained.
Comparison boundaries still under review
The 7.9 mm value concerns the smallest documented mature female of a freshwater species. Broader smallest-fish rankings differ when including marine species, mature males or maximum size by species.
- Verification assessment
- 2026-11-10
- Last editorial review
- 2026-11-10
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