How does the green swordtail see?
The green swordtail (Xiphophorus hellerii) is a fish in the order Cyprinodontiformes. Its eyes belong to the vision type Shallow-water fish tetrachromat.
Measured in this species: motion (flicker fusion). One measured dial: a value other than colour or sharpness is measured in this species; colour and sharpness are not measured here. Every value below carries its evidence level and sources; nothing is typed by hand.
See your photo as the green swordtailThis species is part of the full catalogue in the tool (full unlock). Your photo stays on your device.
What stands out
- It has 6 colour receptor classes, including ultraviolet; people have 3.
- Its sharpest vision resolves 6.7 cycles per degree: the finest stripe pattern it can tell apart from grey.
- Both eyes see the same 32.85° in front of it (binocular overlap), where depth is judged best.
- It stops seeing flicker at 43 Hz, against 60 Hz for people in this dataset, so fast motion looks choppier to it.[9][8]
- Activity pattern: diurnal.
The six dials
Evidence levels: how the tiers work. "Measured" means a value measured in this species; "Estimated" values come from a close relative or an eye-size formula.
| Dial | Value | Evidence | Sources |
|---|---|---|---|
| Colour | Colour receptors 6 receptor classes: 359 nm (UVS), 409 nm (VS/SWS (violet)), 465 nm (SWS (blue)), 529 nm (MWS (green)), 542 nm (LWS (long)), 573 nm (LWS (long)) receptor set of nearest measured relative Poecilia reticulata (same family Poeciliidae) | Estimated | [1][2] |
| Ultraviolet yes: at least one receptor peaks in the ultraviolet | Estimated | ||
| Sharpness | Acuity 6.7 cycles per degree median of 1 relatives in family Poeciliidae: Poecilia reticulata | Estimated | [3] |
| Field of view | Binocular overlap 32.85° group default: median of tier-A values in vision type V18 within phylum Chordata (2 species: Danio rerio, Notemigonus crysoleucas) | Group default | [4] |
| Sharp zones (foveas) | Number of foveas 0 mode of species-v1 relatives in order Cyprinodontiformes: Anableps anableps | Group default | [5] |
| Fovea type split aerial/aquatic retina | Group default | [5] | |
| Night vision | Activity pattern diurnal group default: mode of tier-A values in vision type V18 within phylum Chordata (224 species: Amphiprion ocellaris, Acanthochromis polyacanthus, Acanthurus bahianus, Acanthurus chirurgus, Acanthurus coeruleus… | Group default | [6][7] |
| Rods vs cones cone-dominated | Group default | [6][7] | |
| Motion (flicker fusion) | Flicker fusion frequency 43 Hz median of 1 rows (no bright-light flag) (behavioural/whole-eye ERG rows; all rows: [43.0]) | Measured | [8] |
Related animals
- Guppy same vision type
- Mummichog same vision type
- Amazon molly same vision type
- Bluefin killifish same vision type
- Four-eyed fish same vision type
- Para molly same vision type
More fish: all fish with measured vision data.
Sources
- VPOD in-vivo (MSP / single-cell) lambda max compendium, file scp_cleaned.csv, VPOD GitHub (Frazer et al. 2025 bioRxiv 10.1101/2025.08.22.671864). github.com/VisualPhysiologyDB/visual-physiology-opsin-db/tree/main/scripts_n_notebooks/vpod_ML_workflows/mine_n_match/data_sources/lmax/vpod
- Schweikert LE, Fitak RR, Caves EM, Sutton TT, Johnsen S. 2018. Spectral sensitivity in ray-finned fishes: diversity, ecology and shared descent. J Exp Biol 221:jeb189761. Table S1. doi.org/10.1242/jeb.189761
- Caves EM, Sutton TT, Johnsen S (2017) Visual acuity in ray-finned fishes correlates with eye size and habitat. J Exp Biol 220:1586-1596. Table S1.. doi.org/10.1242/jeb.151183
- Pita D, Moore BA, Tyrrell LP, Fernandez-Juricic E. 2015. Vision in two cyprinid fish: implications for collective behavior. PeerJ 3:e1113.. doi.org/10.7717/peerj.1113
- species_v1:Schwab et al. 2001
- Froese R. & Pauly D. (eds). FishBase, snapshot v25.04 (morphmet, morphdat, species, families tables), distributed as parquet by C. Boettiger for rfishbase.. fishbase.org
- Moura et al. 2024. A phylogeny-informed characterisation of global tetrapod traits addresses data gaps and biases. PLoS Biol 22:e3002658. TetrapodTraits v3.0.1.. doi.org/10.5281/zenodo.22536349
- Inger R, Bennie J, Davies TW, Gaston KJ. 2014. Potential biological and ecological effects of flickering artificial light. PLoS ONE 9(5): e98631. Table 3. doi.org/10.1371/journal.pone.0098631
- Healy K, McNally L, Ruxton GD, Cooper N, Jackson AL. 2013. Metabolic rate and body size are linked with perception of temporal information. Animal Behaviour 86:685-696. Table 1. doi.org/10.1016/j.anbehav.2013.06.018
Every value cites its sources (all sources). Data: catalogue-v1, built 2026-09-29. Accuracy notes: how accurate is this?