# Datasheet for QT26-QC

## Summary

QT26-QC is a 6,719-query, 3,121-taxon evaluation roster for fine-grained fish
recognition. It is designed for fixed-denominator comparison of recognition
systems rather than for training. Images are natural photographs selected by
taxon-independent photo-suitability rules and mapped to FishBase 25.04 keys.

## Composition and lineage

- Canonical split: `test`, 6,719 rows, 3,121 taxa.
- Construction parent: 6,734 rows, 3,126 taxa.
- Exclusion: 15 rows sharing an iNaturalist observation with Q-INT.
- Recorded observation window: 2026-03-01 02:31 UTC to 2026-06-23 06:50 UTC.
- Byte availability: 100% of canonical queries.

The canonical roster, construction parent and exclusion ledger are published as
separate TSV objects. Only the 6,719-row roster is a scoring set.

## Intended use

QT26-QC supports evaluation of image classifiers, embedding retrieval systems
and reference-gallery recognizers. Predictions are mapped to FishBase 25.04
canonical keys and scored on the fixed denominator. The primary endpoints are
query-micro and species-macro top-1; top-5 and top-20 are secondary.

## Known limits

The roster is intentionally taxonomically broad but remains frequency-skewed.
Its timestamps describe the recorded observations, not a universal guarantee
against earlier pixel copies or future pretraining exposure. Geographic and
photographer distributions inherit the public observation pool. It contains
fish photographs judged suitable for recognition and is not an open-set or
fish-adjacent rejection benchmark.

## Rights and provenance

Each row retains its normalized licence, attribution, source page and source
image URL. The canonical licence counts are: 6,255 CC BY-NC; 359 CC BY; 53 CC0;
28 CC BY-NC-ND; 22 CC BY-NC-SA; and 2 CC BY-SA. Users remain responsible for
following the recorded terms.

## Integrity

Parquet image bytes are not resized, cropped or re-encoded. They are checked
against the authoritative roster and the immutable E0 archive by SHA-256.
Checksums, row correspondence and executable verification tools accompany the
release.