The fish family Pegasidae, the “sea moths”, includes just five species (placed in two genera) but is represented in temperate and tropical coastal zones throughout the Indo-Pacific. All sea moths are small (no more than than ~180 mm total length), benthic (bottom-dwelling), and very well camouflaged. They commonly occur in relatively shallow coastal waters in open sand or mud substrate in calm areas. (Palsson and Pietsch 1989, cited in Pajaro et al. 2004)
The Short Dragonfish (Eurypegasus draconis) is the most widely distributed pegasid, occurring throughout the tropical and subtropical Indian Ocean, Red Sea, and western and central Pacific. It is one of several pegasid species that can be found in bays and estuaries. The maximum recorded length is 77 mm. This species has been collected from depths as shallow as 3 m or less, but usually occurs between 37 and 91m (Palsson and Pietsch 1989, cited in Herold and Clark 1993).
Herold and Clark (1993) studied this species in the field (in the Red Sea) and in captivity. They found E. draconis at depths between 1.1 and 18.3 m in areas where coastal coral reefs were disrupted by channels and lagoons and where the bottom consisted of sand and rubble, sometimes with the seagrass Halophila stipulacea, and only occasionally with patches of corals. The authors noted in their observations that individual fish were able to change color to match their background. During the day, fish crawled slowly over the seafloor using their pelvic fins alternately, swimming only if disturbed. They became inactive after sunset and did not resume crawling until after sunrise. To feed, these fish moved their snouts very close to the food. The mouth would then protrude forward and downward, producing an inhalant current that sucked the food item into the mouth. Analysis of stomach contents revealed isopods, isopod eggs, decapod larvae, harpacticoids, copepods, copepod larvae, goby eggs, and stones up to 1 mm in diameter. Polychaetes, nematodes, trematodes, Alpheus (pistol) shrimp, post-veliger mollusks, and foraminiferans were also found.
A curious behavior seen in these fish is that they sheds their skins in one piece, probably every one to five days, a process described in some detail by Herold and Clark (1993). Herold and Clark (1993) also discuss evidence suggesting monogamy in this species, as well as other aspects of social and reproductive behavior.
Although sea moths are not harvested for food, Vincent (1997) estimated that millions of sea moths are sold for traditional medicine each year in China and Hong Kong alone, with supplies coming from China, Vietnam and possibly other areas in Southeast Asia. Live sea moths are sold in the aquarium trade. Pajaro et al. (2004) studied the sea moth fishery in the Philippines, which involves both Eurypegasus draconis and Pegasus volitans. This trade includes both dead fish (taken mostly as bycatch but sold for the traditional medicine trade) and live fish for the aquarium trade. Although the sea moth fishery was not of great economic significance, the very substantial numbers of fish taken may have a seriously negative impact on populations in the Philippines. (Herold and Clark 1993; Pajaro et al. 2004)
- Herold, D., & Clark, E. 1993. Monogamy, spawning and skin-shedding of the seamoth, Eurypegasus draconis (Pisces:Pegasidae). Environmental Biology of Fishes 37: 219-236.
- Pajaro, M. G., Meeuwig, J. J., Giles, B. G., & Vincent, A. C. 2004. Biology, fishery and trade of sea moths (Pisces: Pegasidae) in the central Philippines. Oryx 38(4): 432–438.
- Palsson, W.A. and Pietsch, T.W. 1989. Revision of the Acanthopterygian Fish Family Pegasidae (Order Gasterosteiformes). 38 pp., 8 col. figs. Ichthyology Collection of the Bishop Museum in Honolulu, Hawaii, U.S.A.
- Vincent, A.C.J. 1997. Trade in pegasid fishes (sea moths), primarily for traditional Chinese medicine. Oryx 31 (3): 199-208.