Marble Goby Research Articles

DDT and derivatives in indicator species of the aquatic food web of Rangsit agricultural area, Central Thailand

The presence of DDT and derivatives in the food web of freshwater ecosystems of Rangsit agricultural area, Pathum Thani Province, Thailand were investigated from June 2004 to May 2007. By using gas chromatography (GC) with micro electron capture detector (mu ECD), DDT and derivatives in water, sediment, and fifteen indicator species i.e., 2 producers; Eichhornia crassipes and plankton (phyto- and zoo- plankton), an herbivore; Trichogaster microlepis (3) 3 omnivores; Trichogaster trichopterus, Oreochromis niloticus, and Puntius gonionotus, 6 carnivores; Channa striatus, Oxyeleotris marmoratus, Macrognathus siamensis, Parambassis siamensis, Anabas testudineus, and Pristolepis fasciatus, and 3 detritivores; Macrobrachium lanchesteri, Pomacea sp., and Filopaludina mertensi were measured. Results show low concentration levels (part per billion) of DDT & derivatives in each food web compartment i.e. water, sediment, aquatic plant, plankton, fish, and invertebrates. Magnification patterns, i.e. bioconcentration, bioaccumulation, and biomagnification, based on habitat and foraging behavior of selected freshwater species indicates that DDT & derivatives can accumulate and be magnified through the food chain from the lowest up to the highest trophic level. Therefore, the presence of residues and the evidence of magnification patterns can be observed as ecological indicators for evaluating ecological health risk.

Postprandial nitrogen metabolism and excretion in juvenile marble goby, Oxyeleotris marmorata (Bleeker, 1852)

The objective of this study was to examine postprandial nitrogen metabolism and excretion in the juvenile marble goby, Oxyeleotris marmorata (30–80 g), fed a high protein diet (cod fish fillet). Feeding led to only a slight increase in plasma ammonia concentration and had no significant effect on the ammonia content in the brain of juvenile O. marmorata during the subsequent 24 h. Unlike other fishes, juvenile O. marmorata could apparently avoid postprandial ammonia toxicity, and as a result there was no increase in the brain glutamine content, which decreased significantly instead at certain post-feeding time point. Since no prominent increases in tissue glutamine and urea contents were observed after feeding despite its ability to detoxify ammonia to glutamine during emersion and its possession of a full complement of hepatic ornithine-urea cycle enzymes, it can be concluded that only a moderate amount of ammonia was produced after feeding. Traditionally, it has been accepted that excess amino acid would be degraded in the liver through transdeamination which involves the deamination of glutamate catalyzed by glutamate dehydrogenase (GDH). However, we report for the first time that glutamate content in liver and intestine of juvenile O. marmorata increased to 10.8 µmol g − 1 and 3.3 µmol g − 1 , respectively, 6 h post-feeding. These results indicate that the rate of glutamate catabolism in the liver was lower than the total rate of glutamate released directly from protein degradation and produced indirectly from other amino acids through transamination. Indeed, feeding led to significant increases in hepatic GDH amination activity and intestinal GDH activity, in both amination and deamination directions, in juvenile O. marmorata. Thus, there could be an increase in the capacity of the liver, and perhaps the intestine, to produce and retain glutamate after feeding. As a result, only 33% of the ingested nitrogen was excreted during the 24-h post-feeding period, with 67% being retained for somatic growth. Results obtained from this study can be useful for designing re-circulating aquaculture systems for juvenile marble goby, and they offer insights into mechanisms that can be induced by feeding to retain ingested nitrogen.

EFFECTS OF DIFFERENT TYPES OF FEED ON GROWTH, SURVIVAL AND DIGESTIVE ENZYME ACTIVITY OF EARLY JUVENILE-STAGE MARBLE GOBY, Oxyeleotris marmoratus

The stable mass seed production technique of marble goby, Oxyeleotris marmoratus has not yet been established due to high mortality occurring on the early juvenile stage and/or after 40 days after hatching (d AH). In order to establish the mass seed production technique, O. marmoratus juveniles of 40 d AH were reared for 60 days to determine growth, survival and digestive enzyme activity at different types of feed (trash fish, artificial feed and Artemia sp. nauplii). Specific growth rate (5.32) and survival rate (91.3%) in juveniles fed Artemia sp. nauplii showed significantly higher (P<0.05) than those of juveniles fed trash fish and artificial feed. At the end of the experiment, the mean specific trypsin, amylase and lipase activities of juveniles fed Artemia sp. nauplii were recorded as 0.04 mU mg protein-1m-1, 0.114 mg maltose mg protein-1h-1 and 9.58 m Units, respectively, and they were significantly higher than those of juveniles fed trash fish and artificial feed. In the present study it was shown that O. marmoratus early juveniles had more efficient digestibility and absorption the nutrient when fed with Artemia.

Oxyeleotris marmoratus, Predator or By-Product in Integrated Aquaculture Ponds

Participating farms in the Muang district of Nong Khai Province, were selected for the investigation of management practices and yields of marble goby, Oxyeleotris marmoratus, in integrated culture with Nile tilapia (Oreochromis niloticus). The research took place from February to May, 2007. The observed production of O. marmoratus in integrated aquaculture ponds indicated a wide range of management practices. The yields of Oxyeleotris marmoratus were between 22.1 to 316 kg ha(-1) (average 81+/-78 kg ha(-1)). The farmers tended to prefer Oxyeleotris marmoratus not only as a by-product, but also as the main product from their ponds. Most farmers realized that Oxyeleotris marmoratus predate Nile tilapia fingerlings from the natural spawning of mature Nile tilapia in the ponds. With respect to consumed prey, the frequency of occurrence of prawns was 73.3%, whilst that of small fish was 43.3%. In terms of prey biomass, prawns were also the most abundant food item, giving the relative abundance of 56.0%. A preliminary trial on predation pressure was conducted to confirm the role of Nile tilapia fingerling as live feed for Oxyeleotris marmoratus in integrated aquaculture ponds and it was found that the daily predation pressure was between 1.90 to 2.46 fish day(-1).

Feeding of Marbled Goby, Oxyeleotris marmorata (Blkr.), Larvae in the Two Weeks of Their Early Life

<p class="MsoBodyTextIndent" style="margin: 0cm 0cm .0001pt; text-align: justify;"><span style="font-size: 11pt;" lang="in" xml:lang="in">ABSTRACT</span></p><p class="MsoBodyTextIndent" style="margin: 0cm 0cm .0001pt; text-align: justify;"><span style="font-size: 11pt;" lang="in" xml:lang="in"><br /></span></p><p class="MsoBodyTextIndent" style="margin: 0cm 0cm .0001pt; text-align: justify;"><span style="font-size: 11pt;" lang="in" xml:lang="in">The experiment was carried out at the Laboratory of Aquaculture System and Technology, Faculty of Fisheries, Institut Pertanian Bogor, Bogor. Factorial arrangement in randomised block design was used in this experiment with two factors: kind of feed and feed density for sand goby, <em>Oxyeleotris marmorata</em> (Blkr.) larvae. There were 3 kinds of feed: rotifer, enriched-rotifer, and egg yolk-premix. Rotifer density of 20, 30, and 40 individuals/ml were maintained troughout the experiment. Egg yolk-premix were given per day in equivalent quantity as those rotifers in the treatment. Larvae of 40 individuals/l were kept in the 250 l plastic tanks, filled with 200 l of aerated ground water for 15 days indoor. Larvae fed rotifer showed better survival and growth rate than those fed egg yolk-premix. Increased rotifer density tended to increase survival and growth rate of larvae.</span></p><p class="MsoNormal" style="text-align: justify;"><span style="font-size: 11pt;" lang="in" xml:lang="in">Key words :<span> </span>marbled goby, <em>Oxyeleotris marmorata</em>, larvae, feeding, rotifers</span></p><p class="MsoNormal"><span style="font-size: 11pt;" lang="in" xml:lang="in"> </span></p><h3 style="margin-top: 0cm; text-align: center;"><span style="font-size: 11pt;" lang="in" xml:lang="in">ABSTRAK</span></h3><p class="MsoBodyTextIndent" style="margin: 0cm 0cm .0001pt; text-align: justify;"><span style="font-size: 11pt;" lang="in" xml:lang="in">Percobaan ini dilakukan di Kolam Percobaan Babakan, Laboratorium Bogor, Bogor, dan dirancang berbentuk factorial dalam rancangan acak kelompok, dengan faktor: (1) jenis pakan dan (2) kepadatan pakan. Jenis pakan dibedakan menjadi: rotifera, rotifera-diperkaya, dan kuning telur-premiks, sedangkan kepadatan rotifera dibedakan menjadi : 20,30, dan 40 individu/ml, dipertahankan setiap hari. Kuning telur-premiks diberikan kepada larva ikan betutu, <em>Oxyeleotris marmorata</em> setiap hari yang setara dengan bobot rotifera setiap perlakuan, berdasarkan bobot kering keduanya. Larva sebanyak 40 ekor/l dipelihara dalam tangki plastik bervolume 250 l yang diisi air 200 l selama 15 hari dalam ruangan. Larva yang diberi rotifera cenderung memiliki kelangsungan hidup dan pertumbuhan lebih besar daripada kuning telur-premiks. Kepadatan rotifera yang semakin tinggi cenderung dapat meningkatkan kelangsungan hidup dan pertumbuhan larva.</span></p><p class="MsoNormal" style="text-align: justify;"><span style="font-size: 11pt;" lang="in" xml:lang="in">Kata kunci :<span> </span>ikan betutu, <em>Oxyeleotris marmorata</em>, larva, pemberian pakan, rotifera</span></p>

Effect of Thyroxine Hormone Administration in Female Broodstock on Metamorphosis and Survival Rates of Marble Goby (Oxyeleotris marmorata, BLKR.) Larva

<p>The experiment was conducted to study the effect of thyroxine hormone injection on female marble goby on metamorphosis and survival rate of their larva. Thyroxine hormone was injected into female at the dosage of 0,25 and 50 µg/g body weight. And then the female were reared with males in spawning tanks. Spawned eggs were hatched and the larva was observed for organogenesis, yolk absorption and growth in length. Formation of eye spot, swim bladder and body pigment becoming faster as the increase in thyroxine hormone dose. Yolk volume in larva that was obtained form thyroxine injected female decreased faster than those of control. Thyroxine hormone did not affected length growth and survival rate</p> <p>Key words: Marble goby, broodstock, thyroxine, metamorphosis, survival rate, larva</p>

Waste excretion of marble goby (Oxyeleotris marmorata Bleeker) fed with different diets

Marble goby (Oxyeleotris marmorata Bleeker), with its high demand and price, has a great potential as a profitable commercial aquaculture candidate in Malaysia and Southeast Asia region. Efforts are being made to produce this species in a better controlled culture environment like recirculating aquaculture system (RAS) due to poor growth performance and disease problems shown by conventional cage and outdoor pond culture systems. Quantification of waste excreted by fish is critical to RAS design. This study was conducted to characterize the waste excretion rates of marble goby fed with different diets (live food and minced fish). Ammonia-N (TAN), urea-N, nitrite-N (NO2-N), nitrate-N (NO3-N), total-N (TN), organic-N (ON), feces-N, 5-day biochemical oxygen demand (BOD5) and total suspended solid (TSS) produced from marble goby were determined over a 72-h excretion period. Under given experimental conditions, the results showed that feed type had significant influence on the waste excretion rates, with marble goby fed live tilapia (Oreochromis niloticus) exhibiting significantly (P<0.05) the lowest amount of waste excretion comparable to that of fish fed live common carp (Cyprinus carpio) and minced scads (Decapterus russellii). This indicates that feeding marble goby with tilapia poses less adverse effects on water quality and is thus a suitable diet for this species. The waste excreted by the fish is composed of nitrogenous excretion (TAN, Urea-N, ON, Feces-N), and productions of dissolved biodegradable organic substances (BOD5) and TSS (TSSfeces+TSSwater). About 58–71% of the nitrogen consumed in food was excreted and its rate depended mainly on the feed type. TAN was the chief end-product of protein metabolism; about 74–84% of the daily total nitrogenous excretion was TAN. Urea-N accounted for 13–21% of the daily total nitrogenous excretion indicating that urea-N is an important nitrogenous excretory end-product in marble goby. The waste excretion data presented in this study can be served as a pre-requisite for designing a RAS for this species. The overall BOD5 and TSS production found in this study also point to the need for including bio-filtration unit and suspended solids removal mechanism in the RAS design.

Prey ingestion and live food selectivity of marble goby (Oxyeleotris marmorata) using rice field prawn (Macrobrachium lanchesteri) as prey

Marble goby (Oxyeleotris marmorata), a carnivorous fish native to freshwater in Asia-Pacific region, is a high-valued species in many Asian countries. The present study consisting of three experiments was conducted to determine the appropriate density, size and ingestion time of marble goby fingerlings on rice field prawn (Macrobrachium lanchesteri) as prey. Results showed that the ingestion rate of marble goby fingerlings (0.26–1.43 g size) on prawns (9–12 mm in length) had an asymptotic pattern peaked at a predator to prey ratio of 1:20. Marble goby fingerlings did catch prawns during both daytime (07:00–17:00 h) and nighttime (17:00–07:00 h), but the ingestion peaked during nighttime period. The hourly ingestion rate during nighttime was significantly higher than that during daytime for the smaller-size marble goby fingerlings of 0.26–0.87 g, while there was no significant difference in the hourly ingestion between nighttime and daytime for the larger-size marble goby fingerlings of 1.43 g. The daily ingestion of marble goby fingerlings on prawns (mg consumed prawns/goby/day) increased significantly with increasing average weights (g) of marble goby fingerlings (Y=27.6+47.8X, n=30, r2=0.86, p<0.05). Results also showed that the preferred prawn size of marble goby fingerlings of average weights of 0.26–4.18 g was small (9–12 mm) with positive electivity index of 0.19–0.33, and the shift from small- to medium-size (12–14 mm) prawns was slow. The present study has demonstrated the feasibility of using rice field prawns as live foods to nurse marble goby fingerlings.

Control of Natural Food with Diazinon for Growth and Survival of Marbled Goby, Oxyeleotris marmorata (Bleeker)

&lt;p&gt;Dua percobaan telah dilakukan, yaitu tanpa dan dengan larva ikan. Percobaan pertama, yang menggunakan 3 konsentrasi diazinon 0. 2 dan 4 ppm dan 3 ulangan, mempelajari pertumbuhan rotifera, cladocera dan copepoda. Percobaan kedua mempunyai 2 perlakuan, yaitu diazinon 0 dan 4 ppm (yang terbaik dari percobaan pertama) serta 4 ulangan untuk mengevaluasi: 1) ketersediaan, pemanfaatan dan susunan jasad-jasad pakan, 2) pertumbuhan dan kelangsungan hidup larva, serta 3) perkembangan larva ikan. Larva yang berumur satu hari ditebar pada saat kelimpahan rotifera tertinggi di hapa dengan kepadatan 40 larva/1 atau 3.200 larva/hapa. Hapa (mesh 0,8 mm) yang berukuran 50x40x50 cm ditempatkan dalam kolam-kolam beton yang berukuran 4,25x2,00x 0,65 m. Kolam-kolam ini mula-mula dikeringkan selama 2 hari, dipupuk dengan kotoran ayam 1.000 g/m3 dan diisi air setinggi 50 cm. Keesokan harinya kolam dipupuk dengan urea dan tripel superfosfat masing-masing 20 dan 30 g/m3. Dua hari kemudian air diberi diazinon sesuai perlakuan. Hasil percobaan pertama menunjukkan bahwa diazinon meningkatkan ketersediaan rotifera. Populasi rotifera tertinggi dicapai di kolam yang mendapat diazinon 4 ppm. Percobaan kedua memberikan laju pertumbuhan harian dan kelangsungan hidup larva ikan serta ketersediaan dan pemanfaatan rotifer tertinggi pada pemberian diazinon 4 ppm.&lt;/p&gt; &lt;p&gt;Kata kunci: Pakan alami, larva. &lt;em&gt;Oxyeleotris marmorata, &lt;/em&gt;diazinon. kelangsungan hidup, pertumbuhan&lt;/p&gt; &lt;p&gt; &lt;/p&gt; &lt;p&gt;ABSTRACT&lt;/p&gt; &lt;p&gt;Two experiments were conducted, without and with fish larvae. The first experiment, utilizing 3 concentrations of diazinon, i.e. 0, 2 and 4 ppm and 3 replications, evaluated the growth of rotifers, cladocerans and copepods. The second experiment had 2 treatments, i.e. 0 and 4 ppm diazinon and 4 replications evaluated: 1) the availability, utilization and composition of food organisms, 2) the growth and survival rates offish larvae, and 3) the development of larvae. One-day old larvae were stocked at times of highest rotifer concentrations in hapas at 40 larvae/1 or 3,200 larvae/hapa. Hapas (0,8 mm mesh) of 50x40x50 cm were placed in concrete ponds of 4.25x2.00x0,65 m. The ponds were dried for 2 days, fertilized with chicken manure 1.000 g/m3 and filled with water up to 50 cm deep. Next day, the ponds were fertilized with urea and triple superphosphate 20 and 30 g/m3 respectively. Two days later, the water was treated with diazinon according to treatments. The results of the first experiment showed that diazinon increased the availability of rotifers. The highest rotifer populations were obtained in ponds receiving 4 ppm diazinon. The second experiment gave highest daily growth and survival rates of fish larvae, te availability and utilization of rotifers at 4 ppm diazinon.&lt;/p&gt; Key words: Natural foods, larvae, &lt;em&gt;Oxyeleotris marmorata, &lt;/em&gt;diazinon, survival, growth.

Association between bacterial community structures and mortality of fish larvae in intensive rearing systems

Bacterial community structures were analyzed in water used for rearing fish larvae by fluorescence in situ hybridization. In Experiment 1, red sea bream Pagrus major larvae were reared in two commercial seed production tanks. The survival rate in Tank 1 was higher than in Tank 2, even though phytoplankton, Nannochloropsis sp., was added to both tanks. In Tank 2, γ-proteobacteria became dominant (∼70% of total bacteria) on day 13, there after heavy larval mortalities occurred. In Tank 1, however, α-proteobacteria and the Cytophaga-Flavobacterium cluster were predominant from day − 1 until day 13; no significant mortality was recorded. In Experiment 2, marble goby Oxyeleotris marmoratus larvae were cultured with or without Nannochloropsis sp. At the end of the experiment, larval survival rates in aquaria with Nannochloropsis sp. were significantly (P <0.05) higher than those without. In rearing water without Nannochloropsis sp., γ-proteobacteria increased during rearing. In rearing water with Nannochloropsis sp., α-prote obacteria and the Cytophaga-Flavobacterium cluster were predominant at the beginning of the experiments and the relative abundance of γ-proteobacteria was maintained at a lower level throughout the experiments. The predominance of α-proteobacteria and the Cytophaga-Flavobacterium cluster appears to be a good indicator of successful larval production.

Effect of Triiodothyronine and Cortisol on Development, Growth and Survival Rate of Sand Goby (Oxyeleotris marmorata, Blkr.) Larvae

&lt;p class="MsoBodyText2" style="text-indent: 0cm;"&gt;&lt;span style="font-size: 10pt;" lang="in" xml:lang="in"&gt;ABSTRACT&lt;br /&gt;&lt;/span&gt;&lt;/p&gt;&lt;p class="MsoBodyText2" style="text-indent: 0cm;"&gt;&lt;span style="font-size: 10pt;" lang="in" xml:lang="in"&gt;This experiment was conducted to investigate the effect of triiodothyronine and cortisol on the development, growth, and survival rate of sand goby larvae.&lt;span&gt; &lt;/span&gt;The experiment was carried out at Kolan Percobaan Babakan, Faculty of Fisheries and Marine Sciences, IPB Bogor.&lt;span&gt; &lt;/span&gt;The larvae were immersed in solution of A (T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 1 mg/1), B (T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 0, 1 mgll), C (T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 0,0 1 mg/1) dan D (without hormone) for one hour.&lt;span&gt; &lt;/span&gt;After treatment, larvae were reared in aquarium (50x50x50 cm).&lt;span&gt; &lt;/span&gt;Larvae were fed by rotifer and phytoplankton, three times a day.&lt;span&gt; &lt;/span&gt;Larval development, growth and survival rate were observed.&lt;span&gt; &lt;/span&gt;Result showed that T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 +C 1 nig/1 and T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 0, 1 mg/1 could accelerated development of swim bladder and eyespot of larvae.&lt;span&gt; &lt;/span&gt;Treatment did not effect body pigmentation and growth; but effect survival rate of sand goby larvae.&lt;/span&gt;&lt;/p&gt;&lt;p class="MsoNormal" style="text-align: justify;"&gt;&lt;span lang="in" xml:lang="in"&gt;Key words :&lt;span&gt; &lt;/span&gt;Triidothyronine, cortisol, larvae, sand goby fish, development, growth, survival rate&lt;/span&gt;&lt;/p&gt;&lt;p class="MsoNormal" style="text-align: justify;"&gt;&lt;span lang="in" xml:lang="in"&gt; &lt;/span&gt;&lt;/p&gt;&lt;p class="MsoNormal" style="text-align: center;" align="center"&gt;&lt;span lang="in" xml:lang="in"&gt;ABSTRAK&lt;/span&gt;&lt;/p&gt;&lt;p class="MsoNormal" style="text-align: justify;"&gt;&lt;span lang="in" xml:lang="in"&gt;Penelitian ini bertujuan untuk mengetahui pengaruh pemberian hormon triidotironin dan kortisol terhadap perkembangan, pertumbuhan dan kelangsungan hidup larva ikan betutu.&lt;span&gt; &lt;/span&gt;Penelitian ini dilakukan di Kolam Percobaan Babakan, Fakultas Perikanan dan Ilmu Kelautan, Institut Pertanian Bogor.&lt;span&gt; &lt;/span&gt;Larva direndam selama satu jam dalam larutan A (T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 1 mg/1), B (T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 0, 1 mg/1), C (T&lt;sub&gt;3&lt;/sub&gt; 2 mg/1 + C 0,0 1 mg/1) dan D (tanpa hormon).&lt;span&gt; &lt;/span&gt;Setelah perlakuan, larva dipelihara dalam akuariun berukuran 50x50x50 cm.&lt;span&gt; &lt;/span&gt;Selama pemeliharaan larva diberi pakan berupa rotifer dan fitoplankton dengan frekuensi tiga kali sehari.&lt;span&gt; &lt;/span&gt;Perkembangan, petumbuhan, dan kelangsungan hidup larva diamati.&lt;span&gt; &lt;/span&gt;Perendaman larva ikan betutu dalam larutan A dan B dapat mempercepat pembentukan gelembung renang dan bintik mata.&lt;span&gt; &lt;/span&gt;Perlakuan yang diberikan tidak mempengaruhi kecepatan terjadinya pigmentasi tubuh dan pertumbuhan, tetapi mempengaruhi derriat kelangsungan hidup larva.&lt;/span&gt;&lt;/p&gt;&lt;p class="MsoNormal"&gt;&lt;span lang="in" xml:lang="in"&gt;Kata kunci :&lt;span&gt; &lt;/span&gt;Triidotironin, kortisol, larva, ikan betutu, perkembangan, pertumbuhan, kelangsungan hidup&lt;/span&gt;&lt;/p&gt;

Changes in sperm motility in response to osmolality/Ca 2+ in three Indonesian fresh water teleosts: Goby ( Oxyeleotris marmorata), Java carp ( Puntius javanicus), and catfish ( Clarias batrachus)

Sperm of most fresh water teleosts become motile when released into the hypotonic fresh water environment, but the role of osmolality and Ca 2+ on sperm motility is not clear. Osmotic pressure and Ca 2+ concentrations increase from fresh water to brackish water. Java carp Puntius javanicus and catfish Clarias batrachus live and reproduce only in fresh water. On the other hand, goby Oxyeleotris marmorata can acclimate and reproduce from fresh water to brackish water. In the present study, sperm motility and trajectory were compared among these three Indonesian endemic species. Sperm of Java carp, goby, and catfish begun to move in the hypotonic condition (< 200 mOsm/kg). However, the response to Ca 2+ was different among these teleosts. In the presence of Ca 2+, Java carp sperm swam in circular paths and immediately become quiescent, suggesting that Java carp sperm motility is activated in hypotonic aquatic environment without Ca 2+. Goby sperm swam straightforward in the presence or absence of Ca 2+. Percentages of motile sperm increased in 100–200 mOsm/kg but suppressed by removal of Ca 2+. Regarding sperm motility and trajectory, no response was found in catfish sperm. These results suggest that a response to Ca 2+ is different among sperm of the three species and suited to their habitat.

Cove culture of marble goby ( Oxyeleotris marmorata Bleeker) and carps in Tri An Reservoir of Vietnam

This study was conducted in the 5.24-ha Truong Dang Cove of Tri An Reservoir of Vietnam during June 2002–May 2003 to describe cove culture of marble goby ( Oxyeleotris marmorata Bleeker) with silver carp ( Hypophthalmichthys molitrix), bighead carp ( Aristichthys nobilis), common carp ( Cyprinus carpio) and grass carp ( Ctenopharyngodon idella) stocked at 960, 470, 470, 470 and 170 fish/ha, respectively. After about 7 months of culture period from October 2002 to May 2003, gross yield of marble goby was 251.1 kg/ha/crop, while gross yields of silver carp, bighead carp, common carp and grass carp were 90.5, 114.3, 84.6 and 35.0 kg/ha/crop, respectively. Survival was 73.7% for marble goby and 55.1–62.8% for carps. Results indicated that the cove had relatively good physicochemical conditions with diversified natural food resources such as terrestrial vegetation, phytoplankton, zooplankton, benthos, detritus, small wild fish and prawns. The major food item of marble goby was small freshwater prawns, followed by small wild fish and benthos. Addition of marble goby to carp polyculture in cove gave much higher economic return, compared to that without marble goby (US$2713.2 vs. US$260/crop). This study has demonstrated that cove culture of marble goby is a prominent prospect ecologically, technologically and economically.

Effects of Added Shelter and Stocking Density on Growth of Sleepy Cod Oxyeleotris lineolatus in Ponds

AbstractSleepy cod Oxyeleotris lineolatus is a species of freshwater goby in demand in Australian markets by consumers of Asian origin. It is related to marble goby Oxyeleotris marmoratus, the most expensive freshwater food fish in Asia, which is cultured throughout southeast Asia in ponds and cages. The performance of sleepy cod in culture conditions was investigated to assess the viability of farming them in northern Australia. Sleepy cod fingerlings (62.8 ± 0.8 mm total length and 2.56 ± 0.095 g) were stocked into experimental ponds at 32,857 fish/ha, and grown out for 8 mo. Shelter was provided in each of three replicate ponds and was absent in three control ponds. The provision of shelter in juvenile growout was found to be of no benefit, although fish in ponds provided with shelter weighed slightly more per unit length than fish in ponds without shelter. Cannibalism was not a problem in growout, and survival was close to 100%. After the shelter trial was completed, fish were graded into large and small classes (three replicates of each), and grown out without shelter at the same density for 158 d. Following that, fish were again graded, and the largest 30% retained from growout at a density of 8,857 fish/ha (large, 198 ± 6.44 g) or 10,000 fish/ha (small, 48.9 ± 1.27 g). These were grown out for 188 d. Growth of selected stock at low densities was slower than earlier growth rates, although smaller fish gained weight more rapidly than larger fish. Growth rates were better than the only published data for marble goby. Further investigation into high density culture and different genotypes of sleepy cod needs to be undertaken to determine the viability of pond culture.

The loach Misgurnus anguillicaudatus reduces amino acid catabolism and accumulates alanine and glutamine during aerial exposure.

The loach Misgurnus anguillicaudatus inhabits rice fields in Southern China. It encounters drought during summer and ammonia loading during agricultural fertilization. In the laboratory, aerial exposure led to decreases in its ammonia and urea excretion. Ammonia accumulated to very high levels in the muscle and liver. Urea synthesis through the ornithine-urea cycle was not involved in ammonia detoxification in M. anguillicaudatus. However, M. anguillicaudatus was capable of partial amino acid catabolism leading to the accumulation of alanine in the first 24 h of aerial exposure. This was apparently coupled to a possible decrease in protein/amino acid catabolism. These are not detoxification mechanisms but mechanisms that avoid internal fouling by ammonia. Misgurnus anguillicaudatus was also capable of detoxifying internally produced ammonia in part to glutamine, which appears to be an important adaptation after 24 h of aerial exposure. However, unlike the case of the marble goby (Oxyeleotris marmoratus), there was no alteration to the kinetic properties of the hepatic glutamine synthetase. During dry seasons, M. anguillicaudatus moves actively on land until it encounters soft mud in which it can bury itself through several strong wriggling actions of the body. Hence, it is possible that M. anguillicaudatus uses partial amino acid catabolism to fuel its short period of activities on land and switches to the formation of glutamine to detoxify internally produced ammonia when it remains relatively inactive in the mud.

The marble goby oxyeleotris marmoratus activates hepatic glutamine synthetase and detoxifies ammonia to glutamine during air exposure

Ammonia levels in various tissues of the marble goby Oxyeleotris marmoratus remained constant throughout a 72 h period of air exposure. The rate of ammonia excretion in these experimental fish decreased to approximately one-fifth of that of the submerged control. Ammonia was not converted to urea during air exposure because there were no significant increases in urea content in the tissues. Also, urea excretion rate was lowered to one-fiftieth that of the submerged fish. After 24 h of air exposure, there was a significant increase in muscle glutamine content, which peaked at 48 h. The increase in glutamine content could account for the decreases in the amounts of ammonia and urea excretion during air exposure. The specific activities of hepatic glutamate dehydrogenase (amination) and glutamine synthetase in these experimental fish increased threefold and thirtyfold, respectively, in comparison with the submerged controls. Thus, O. marmoratus appears to be the first known teleost that responds to air exposure by activating hepatic glutamine synthetase to detoxify internally produced ammonia.

Two new species ofPseudodactylogyroides Ogawa, 1986 (Monogenea) from two species of eleotridid fishes of Peninsular Malaysia

Two new species of monogeneans were collected:Pseudodactylogyroides marmoratae n. sp. from the gills of a freshwater eleotridid,Oxyeleotris marmorata; andP. butisensis n. sp. from a marine eleotridid,Butis butis. They are attributed to the genusPseudodactylogyroides Ogawa, 1986 based on the presence of two pairs of anchors (a large pair and a very small pair) and patches on the large pair. The two small anchors are not needle-like, as inPseudodactylogyroides apogonis, the only previously known species of the genus, but have definite anchor-like features. Descriptions of these two new species are presented. Examinations of the oncomiracidia and post-larvae of the specimens fromO. marmorata revealed that the small anchors develop before the large anchors. On the basis of the present observation the diagnostic characteristics of the genusPseudodactylogyroides are amended.

CHROMOSOMAL CHARACTERS OF THE INDONESIAN SAND GOBY, OXYELEOTRISMARMORATA BLKR. 1874 (ELEOTRIDAE)*)

Karyomorphological investigation of sand goby or marble sleeper (Oxyeleotris marmorata Blkr.) from Cirata Reservoir, West Java, Indonesia was undertaken to determine the modal chromosome number and fundamental number, and to construct the karyotype from somatic metaphase cells of head kidney. A total of 30 fish samples from Cirata Reservoir was sacrificed for direct chromosome preparation by colchicine-citrate-aceto-methanol-Giemsa staining-air drying technique. Chromosome set analysis showed that the modal chromosome number of the test fish is 2n = 46, confirming previous studies. Fundamental number is 50. Two karyotypic formulas were found, i.e. 1) 2n = 46 (4SM + 42A); and 2) 2n = 46 (2M + 2SM + 42A). Key Words: Freshwater fishes, Chromosome analysis, Oxyeleotris marmorata, Indonesia

Development of Sense Organs and Mouth and Feeding of Reared Marble Goby &lt;i&gt;Oxyeleotris marmoratus&lt;/i&gt; Larvae

Development of Sense Organs and Mouth and Feeding of Reared Marble Goby &lt;i&gt;Oxyeleotris marmoratus&lt;/i&gt; Larvae

Egg Development, Hatching, and Larval Development of Marble Goby &lt;i&gt;Oxyeleotris marmoratus&lt;/i&gt; under Artificial Rearing Conditions

Egg Development, Hatching, and Larval Development of Marble Goby &lt;i&gt;Oxyeleotris marmoratus&lt;/i&gt; under Artificial Rearing Conditions