Swamp Eel Monopterus Albus Research Articles

Performance assessment for determining malachite green and leucomalachite green in swamp eel (Monopterus albus) muscle using assigned reference values in a proficiency test

This paper presents the results of a proficiency test (APLAC T058) for malachite green (MG) and leucomalachite green (LMG) in swamp eel (Monopterus albus). The programme was organized by the Hong Kong Government Laboratory and Hong Kong Accreditation Service (HKAS), under the auspices of the Asia-Pacific Laboratory Accreditation Co-operation (APLAC) in 2007. Results submitted by participants were compared with the assigned reference values, which were determined by an accurate liquid chromatography-isotope dilution mass spectrometry (LC-IDMS) technique, and their performance was evaluated on the basis of z-score index. The distribution of data was very wide and discrepancy from the assigned reference values was found to be method dependent. Only 48% and 62% of participants achieved satisfactory z-scores (i.e. ) for MG and LMG, respectively. With the provision of reference values, the programme served to establish an external quality control mechanism for assessing the measurement capabilities of participating laboratories in the determination of MG and LMG in eel samples.

Cryptic diversification of the swamp eel Monopterus albus in East and Southeast Asia, with special reference to the Ryukyuan populations

The swamp eel Monopterus albus is widely distributed in tropical and subtropical freshwaters ranging from Southeast Asia to East Asia, and is unique in its ability to breathe air through the buccal mucosa. To examine the genetic structure of this widespread species, molecular phylogenetic analyses of mitochondrial 16S rRNA sequence (514 bp) were conducted for 84 specimens from 13 localities in Southeast and East Asia. The analyses showed clearly that this species can be genetically delineated into three clades based on geographical populations [China-Japan (Honshu + Kyushu), Ryukyu Islands, and Southeast Asia clades], with each clade exhibiting its own reproductive behavior. Therefore, “M. albus” is believed to be composed of at least three species. The Southeast Asia clade with the highest genetic diversity may include more species. The Ryukyu clade was estimated to have diverged more than 5.7 million years ago, suggesting that the Ryukyuan “M. albus” is native. In contrast, in the China-Japan clade, all haplotypes from Japan were closely related to those from China, suggesting artificial introduction(s).

Induced spawning in the swamp eel (Monopterus albus) using human chorionic gonadotropine and artificial rain stimulation

Induced spawning in the swamp eel (Monopterus albus) using human chorionic gonadotropine and artificial rain stimulation

Autonomic control of the heart in the swamp eel (Monopterus albus) during water-breathing, air-breathing and aestivation

Autonomic control of the heart in the swamp eel (Monopterus albus) during water-breathing, air-breathing and aestivation

A NEW SPECIES OF DENTIPHILOMETRA (NEMATODA: PHILOMETRIDAE) FROM THE MUSCULATURE OF THE GRAY SNAPPER LUTJANUS GRISEUS (OSTEICHTHYES) OFF THE CARIBBEAN COAST OF MEXICO

A new nematode, Dentiphilometra lutjani n. sp. (Philometridae), is described from gravid females (the male is unknown) collected from the body musculature of the marine perciform fish gray snapper, Lutjanus griseus (Lutjanidae), from the Bay of Chetumal and southern coast of Quintana Roo, off the Caribbean coast of Mexico. The new species differs from the only other congener, Dentiphilometra monopteri, from the swamp eel Monopterus albus in China, mainly in the body length of gravid female (15.40-53.21 mm), the shape of the posterior body end (not markedly narrowed, with low caudal projections), the esophageal gland (maximum width near its posterior end), and the length (344-483 microm) of larvae from the uterus; both species also differ in their host types (marine perciform fish vs. freshwater swamp eel) and geographical distribution (Mexico vs. China).

Diet of the Nonindigenous Asian Swamp Eel in Tropical Ornamental Aquaculture Ponds in West‐Central Florida

AbstractThe nonindigenous Asian swamp eel Monopterus albus is established in west‐central Florida, where it invades tropical ornamental fish production ponds. The economically valuable ornamental fish industry (US$42 million in 2003) is dominated by the production of small‐bodied fishes cultured at high densities in small, earthen ponds. Although introduced Asian swamp eels have been described as voracious predators of fish, to date there have been no published studies containing quantitative diet information on any of the introduced populations found in the USA. The purpose of our study was to evaluate the possible effect of nonnative Asian swamp eels on the aquaculture industry by analyzing the diets of Asian swamp eels that have invaded small ponds used for the culture of ornamental fishes. We examined 71 Asian swamp eels ranging from 94 to 864 mm in total length (TL) that were taken from ornamental aquaculture farms. Fifty‐two percent lacked stomach contents; otherwise, prey were relatively small and generally few in number, resulting in low values of stomach fullness. Prey items included amphipods, crayfish, fish, fish eggs, insects, oligochaetes, organic material, plant material, and a tadpole. Insects were the most frequently occurring prey and fish were second. Fish eggs dominated by number but were found in only two individuals. Fish was the heaviest prey category, closely followed by insects, fish eggs, and crayfish. Only 10 fish prey were found in 8 Asian swamp eels (including a cannibalized individual), primarily in the largest predators (≥570 mm TL). Our diet results were surprising, given the highly vulnerable prey fish found in the sampled ponds. We conclude that this species represents a low threat to the Florida ornamental aquaculture industry. We recommend that producers continue to use best management practices, but aggressive control or eradication of Asian swamp eels is not warranted.

Effectiveness of Atimycin‐A as a Toxicant for Control of Invasive Asian Swamp Eels

AbstractThe Asian swamp eel Monopterus albus is native to southeast Asia but has established populations in several locations within the United States. These eels grow up to 1 m long and may prey on or compete with native fishes and amphibians. Additionally, these eels are obligate air‐breathers, can survive long periods out of water, and will travel over land in search of new habitats when necessary. As early as 1990, Asian swamp eels were introduced to several ponds at a local nature center near Atlanta, Georgia, within the Chattahoochee River drainage basin; individuals have since migrated to an adjacent marsh of the Chattahoochee River. Because this population is relatively contained, several methods for control, containment, and possible eradication are being investigated. Juvenile and adult swamp eels primarily obtain oxygen through surface air, although very young eels absorb oxygen directly through their skin. Because they are obligate air‐breathers, standard piscicides (e.g., rotenone and antimycin‐A) that are transmitted across the gill membrane may not be effective. Nonetheless, we tested the effectiveness of antimycin‐A on 2–3‐week‐old Asian swamp eels in case transmission occurred across the epidermis. We tested antimycin‐A concentrations of 2, 5, 10, and 100 nL/L (ppb). No concentration was effective at killing Asian swamp eels, although golden shiners Notemigonus crysoleucas were susceptible at 10 nL/L. Eels that have not undergone metamorphosis (<10 d old) may be susceptible to piscicides such as antimycin‐A, but the lack of effectiveness at the early life stage we tested indicates that eradication through such toxicants probably is not a feasible control method.

Biochemistry and physiology of brain ammonia.

Biochemistry and physiology of brain ammonia.