Macrotrema caligans

(Cantor 1849) Regan 1912

Macrotrema caligans
Macrotrema caligans from Singapore. Photograph by H.H. Tan. ZRC 56698 of 24.5 cm standard length


The common name is pink mud-eel (Tan et al. 2018).


Symbranchus caligans  Cantor 1849


Thailand, Malaysia, Singapore


Syntypes: BMNH 1860.3.19.943 (2) one listed as holotype by Rosen and Greenwood 1976:50


Thailand, Malaysia and Singapore (Kottelat 1989).



Freshwater and brackish water.


The genus is monotypic and is placed in the monotypic subfamily Macrotreminae by Rosen and Greenwood (1976:50).

Biological Notes

Found up to a meter deep in the mud, collected during spring tide (Ng 2018 at Fishbase).

According to Fishbase the male guards and builds a nest or burrow and they source this information from Breder and Rosen (1966). However, my own copy of this book makes no specific mention of this species! It is likely that this description refers to the Family Synbrachidae and not specifically to this species. The diagram on page 654-655 (which Fishbase use as their information source) only refers to the Family. It is highly unlikely that anyone known anthing at all about the reproduction of this very poorly known fish.

Conservation Status


Museum Holdings

As above plus:

BMNH 1908.7.13:1

MCZ 47107 (Rosen and Greenwood 1976:50)

ZRC 41645 (Juvenile 4.5cm TL, Singapore River 1996) (Tan et al. 2018)

ZRC 54090/CMBS 58237 (Juvenile 5.4cm TL, Pasir Ris eastern shore between mouth of Sungei Api Api and Sungei Tampines 2012 (Tan et al. 2018)

ZRC 54755/SEA 4073 (One specimen, 13.6cm SL, Johor Strait, western entrance between 1°19.911’N 103°37.657’E and 1°19.705’N 103°37.544’E, obtained by rectangular dredge over substrate of sand, mud and fine shells, between 7.7 and 7.5 m depth 2014) (Tan et al. 2018)

ZRC 54756/SEA 4056 (One specimen, 10.2cm TL, Johor Strait, western entrance between 1°19.616’N 103°37.588’E and 1°19.397’N 103°37.505’E (DR 287); obtained by rectangular dredge over substrate of sand, mud and fine shells, between 7.6 and 8.7 m depth, 2014) (Tan et al. 2018)

ZRC 56698 (Twenty-one specimens (16.2 - 25.2 cm TL, Lim Chu Kang mudflats, purchased from a bait shop in Singapore 2017) (Tan et al. 2018)

ZRC 56811 (Fifteen specimens (13.6 - 23.0 cm TL), Lim Chu Kang mudflats, purchased from a bait shop in Singapore 2018) (Tan et al. 2018)


Internet Resources

Fishbase page

Photograph by P.Y.C. Ng at Fishbase

Photograph by P.Y.C. Ng at Fishbase

Key References

Cantor, T.E. Journal Article 1849 Catalogue of Malayan fishes
von Martens, E. Book Section 1876 Die Preussische expedition nach Ost-Asien. Nach amtlichen quellen
Regan, C.T. Journal Article 1912 The anatomy and classification of the symbranchoid eels
Herre, A.W.C.T. Journal Article 1940 Additions to the fish fauna of Malaya and notes on rare or little known Malayan and Bornean fishes
Kottelat, M. Journal Article 1989 Zoogeography of the fishes from Indochinese Inland waters with an annotated check-list
Anonymous Web Page 2012 Pink mud eel
Musikasinthorn, P. Book Section 2013 Synbranchidae.
Kottelat, M. Book 2013 The Fishes of the Inland Waters of Southeast Asia: A catalogue and core bibliography of the fishes known to occur in freshwaters, mangroves and estuaries
Lim, K.K.P. Journal Article 2017 The mangrove swamp eel, Ophisternon bengalense, in Singapore
Tan, H.H., Lim, K.K.P. and Ng, P.Y.C. Journal Article 2018 Recent records of the pink mud-eel in Singapore
Head and anterior body of Mancrotrema calligans 24.5 cm standard length from ZRC 56698. Dorsal view at top, lateral view at middle and ventral view at bottom. Note the extensive gill membrane, poorly.developed subcutaneous eyes and distinct lateral line. Photo by H.H. Tan