Cottus perifretum

{{Short description|Species of fish}}

{{Speciesbox

| image = Cottus perifretum.jpg

| status = LC

| status_system = IUCN3.1

| status_ref ={{cite iucn |author=Freyhof, J. |author2=Kottelat, M. |date=2008 |title=Cottus perifretum |volume=2008 |page=e.T135511A4135554 |doi=10.2305/IUCN.UK.2008.RLTS.T135511A4135554.en |access-date=12 November 2021}}

| taxon = Cottus perifretum

| authority = Freyhof, Kottelat and Nolte, 2005

| synonyms =

}}

Cottus perifretum, the bullhead or miller's thumb, is a species of freshwater ray-finned fish belonging to the family Cottidae, the typical sculpins. It is found on both sides of the English Channel, native to Great Britain. It also inhabits Atlantic drainages from the Garonne River (tributaries draining from Massif Central) to the Scheldt in France and Belgium, and the Moselle and Sieg in Germany. It is considered invasive in the Rhine drainage in Germany and the Netherlands. This invasive population in the Rhine is an intermediate between this species and Cottus rhenanus.{{cite journal | author1 = Jörg Freyhof | author2 = Maurice Kottelat | author3 = Arne Nolte | name-list-style = and | year =2005 | title = Taxonomic diversity of European Cottus with description of eight new species (Teleostei: Cottidae) | journal = Ichthyological Exploration of Freshwaters | volume = 16 | pages = 107–172}} Although this species is native to England and Wales it is considered to be a non-native invasive species in Scotland.{{cite journal | author1 = Jenny McLeish | author2 = Rob A. Briers | author3 = Jennifer A. Dodd | author4 = Sonja Rueckert | year = 2020 | title = First genetic evidence that invasive bullhead (Cottus L. 1758) in Scotland is of English origin and the difficulty of resolving the European Cottus species taxonomy | journal = Journal of Fish Biology | volume = 96 | issue = 3 | pages = 617–630 | doi = 10.1111/jfb.14247| pmid = 31893567 | bibcode = 2020JFBio..96..617M | s2cid = 209539657 | url = https://napier-repository.worktribe.com/preview/2495343/First%20genetic%20evidence%20that%20invasive%20bullhead.pdf }}

This species was described as a separate species from the European bullhead (C. gobio) in 2005 by Jörg Freyhof, Maurice Kottelat and Arne W. Nolte.{{cite journal | author1 = Jörg Freyhof | author2 = Maurice Kottelat | author3 = Arne Nolte | name-list-style = and | year =2005 | title = Taxonomic diversity of European Cottus with description of eight new species (Teleostei: Cottidae) | journal = Ichthyological Exploration of Freshwaters | volume = 16 | pages = 107–172}} The specific name perifretum is a combination of peri, meaning "around", and fretum, meaning "straits", an allusion to the species distribution on either side of the English Channel, called Fretum Gallicum in Latin.{{cite web | url = https://etyfish.org/perciformes20/ | title = Order Perciformes: Suborder Cottoidea: Infraorder Cottales: Family Cottidae (Sculpins) | work = The ETYFish Project Fish Name Etymology Database | editor1= Christopher Scharpf | editor2 = Kenneth J. Lazara | name-list-style = amp |date = 22 October 2022 | access-date = 18 January 2023 | publisher = Christopher Scharpf and Kenneth J. Lazara}}

It reaches a maximum length of 13.4 cm.{{FishBase species |genus= Cottus|species= perifretum| month = February | year = 2014}} It prefers small streams to medium-sized rivers.