Giant blenny

Scartichthys gigas is a small rocky-shore fish of the blenny family whose range runs from Panama to northern Chile in the eastern Pacific ^[1]. In Peru it has been studied mainly for its parasites, in fish from Lima ^[2]. The IUCN rates it as Least Concern (LC) ^[3].

A 2021 genetic and morphological study sorts the members of the genus by two main traits: the number of incisor teeth and the colouration. Scartichthys gigas has fewer than 73 incisors and usually 17 rays in the dorsal fin ^[1]. Only two colour patterns matched that incisor count: a reticulated one and one with two bars and a covered head; reticulated specimens had a mean total length of 156 mm ^[1]. Across all fish in the study, of several species, total length ran from 50 to 246 mm, and adults of the genus can reach 300 mm ^[1]. Another source gives 251 mm as the species' maximum length and 13 cm as the size at maturity ^[4].

Uniform orange-brown juveniles, which used to be assigned to this species, are in fact juveniles of Scartichthys viridis ^[1]. The colour of a young fish therefore does not suffice to name it; the study's main criterion is counting the incisors and the dorsal-fin rays ^[1].

Similar species

• Scartichthys viridis: It has more than 73 incisors and usually 18 dorsal-fin rays; one of its patterns is light and dark bluish green ^[1].
• Scartichthys variolatus: It lives only on the Chilean oceanic islands, has between 80 and 93 incisors and round red spots on the head and body ^[1].

The species ranges from Panama (9° N) to Antofagasta in northern Chile (23° S) ^[1]. It overlaps with Scartichthys viridis only between about 14° S and 23° S ^[1]. From the Peruvian locality of San Juan de Marcona the study obtained colouration data only ^[1].

It is a shallow rocky-coast fish: the FishBase entry places it between 0 and 10 m depth ^[4]. The genetic study collected fish between 0 and 15 m ^[1].

It is oviparous and the eggs are laid in mollusc shells or on rocks; the larvae are planktonic and are often found in shallow coastal waters ^[4]. The same source gives plants, small molluscs and crustaceans as its food ^[4].

Fishes of the genus are known in English as drunk blennies ^[1]. In Lima, in a series of 72 fish from the Chorrillos fish terminal gathered between September 2008 and August 2009, fish size was correlated with the number of parasite species ^[2].

Parasites are the best-documented part of its ecology in Peru. In the 72 fish from Chorrillos, 4 parasites were found: an isopod, a copepod, a digenean (Zoogonus rubellus) and a nematode; the copepod occurred in about 56 % of the fish and the digenean in about 26 % ^[2]. The sex of the fish was not related to parasite abundance or prevalence ^[2].

Another study examined 215 fish, 147 males and 68 females, from the Chorrillos fish terminal between June 2013 and March 2014 and found 6 species of helminths: 3 digeneans, 2 nematodes and the cystacanths of an acanthocephalan ^[5]. Three of them, 2 digeneans and 1 nematode, were new records for Peru ^[5].

The IUCN assessed the species in 2007 and places it in the Least Concern (LC) category ^[3]. FishBase repeats that category and notes a minor commercial fishery ^[4].

Not medical advice. For a sting, a poisoning or an allergy, seek medical care.

FishBase states that a soup called borracho is made from the species, said to cause a mild intoxication and a short-lived tiredness ^[4]. The genetic study mentions a belief in effects from eating these fish and calls it unfounded ^[1].

FishBase notes a minor commercial fishery ^[4]. The fish in the Lima parasite studies, 72 in 2008 and 2009 and 215 in 2013 and 2014, were obtained at the Chorrillos fish terminal ^[2],[5].

The genetic study collected fish between 0 and 15 m depth and recorded the colouration of fish at San Juan de Marcona, in Peru ^[1].