饲料中添加胆碱对黄鳝生长、组织脂肪含量及消化酶活性的影响

研究了饲料中添用不同含量胆碱对黄鳝生长、饲料利用效率、肌肉和肝脏脂肪含量、肝体指数及消化器官4种消化酶活性的影响。结果表明，饲料中添加的胆碱含量不同，对黄鳝的影响不同，饲料中胆碱添加量在0～2.0％内，随着胆碱添加量的提高，黄鳝的生长速度会加快，饲料系数会逐步降低，肌肉、肝脏的脂肪含量及肝体指数降低，前肠、后肠和肝脏的蛋白酶、胰蛋白酶、淀粉酶和脂肪酶的活性均会相应的提高，而且饲料中的添加量达0.8%～1.0％时，这些变化显著，表明胆碱对黄鳝是不可缺少的，黄鳝饲料中胆碱的适宜添加量为0.8%～1.0％。     

Insemination, fertilization and gamete management in tench, Tinca tinca (L.)

Various procedures for artificial insemination in tench, Tinca tinca (L.) were re-examined with evaluation of fecundity of males and females among different tench strains. The objectives of this study were to enhance fertilization and hatching rates through optimization of the activation solution, the insemination process, the activation of gametes, and the elimination of eggs stickiness. Sperm for all experiments was collected directly into immobilization solution of modified Kurokura solution containing 180 mM of NaCl and stored at 2 °C for 2.5–5 h prior to the experiment. When dechlorinated tap water was used for activation a gamete ratio of 1150 spermatozoa per egg showed the best significant fertilisation and hatching rates. Optimal ratio between eggs (weight in g) and activation solution (in cm³) was 1:1. Different concentrations of activation solutions such as NaCl from 0 to 68 mM (0–136 mOsmol kg⁻¹) without buffer statistically decreased fertilization and hatching rates. The activation solution containing 17 mM of NaCl, 10 mM Tris–HCl, pH 8 and 9 significantly increased fertilization and hatching rates compared to dechlorinated tap water of pH 7 or activation solution containing 17 mM of NaCl, 10 mM Tris–HCl, pH 6 and 7. Adhesiveness of the eggs was successfully removed by incubation in Alcalase and activity: 3.16 Anson units per cm³.     

暗纹东方鲀生殖洄游期性腺发育特点及人工繁殖的研究

１９９６～１９９８年,作者从长江下游扬中段采捕暗纹东方鱼屯亲鱼,经暂养促熟处理（微流水刺激、投喂鲜活饵料、不定期注射适量的ＬＨＲＨ－Ａ２）,雌鱼的性腺可发育到Ⅳ期末,对外源激素能引起正常的排卵反应。同时观察了Ⅲ、Ⅳ、Ⅴ期性腺发育的特点。催产药物为ＬＨＲＨ－Ａ２和ＰＧ,三针注射,雌鱼剂量为３５ｍｇＰＧ＋６０μｇＬＨＲＨ－Ａ２／ｋｇ,雄鱼剂量减半。在水温１８～２２℃的条件下,效应时间为１０～３６小时;在２１～２２℃时,胚胎发育时间为１３９～２１０小时。１９９７～１９９８年的平均受精率为８３４％,平均孵化率为７８０％。     

Effect of cryoprotectants, extenders and freezing rates on the fertilization rate of frozen striped catfish, Pangasius hypophthalmus (Sauvage), sperm

The effects of four cryoprotectants (methanol, MeOH; dimethyl sulphoxide, DMSO; dimethyl acetamide, DMA; and ethylene glycol, EG), three extenders (calcium‐free Hanks' balanced salt solution, C‐F HBSS, Hanks' balanced salt solution, HBSS and sodium chloride, NaCl) and two different freezing procedures (one‐ and two‐step) on the cryopreservation of striped catfish (Pangasius hypophthalmus (Sauvage)) sperm were investigated. Sperm were frozen using a controlled‐rate freezer in 250 μL straws and stored for 2 weeks in a liquid nitrogen (LN₂) container. They were then airthawed at room temperature, and fertilization, motility and viability were assessed. The highest fertilization rate of 41% (81% of control) was achieved with the combination of 12% DMSO and 0.9% NaCl using a one‐step freezing procedure (10°C min^?1). Also, DMA resulted in a higher fertilization rate (30% or 51% of the control) than MeOH (18% or 38% of the control) or EG (8% or 12% of the control). In addition, the three extenders used did not affect fertilization rates after cryopreservation with each cryoprotectant. There were no significant differences among the three cryoprotectant concentrations and between the one‐ and two‐step freezing procedures. However, fertilization rates of cryopreserved sperm were significantly lower than the controls (P<0.05). The results of this study indicate that high fertilization rates of striped catfish eggs can be achieved using cryopreserved sperm when frozen at 10°C min^?1 in DMSO or DMA with either 0.9% NaCl or C‐F HBSS.     

Relationship between daily survival rates of larval Japanese anchovy (Engraulis japonicus) and concentrations of copepod nauplii in the Seto Inland Sea, Japan

We attempted to estimate the survival rates of larval cohorts (3–15 mm in body length) of the Japanese anchovy Engraulis japonicus population in Hiuchi‐nada, Seto Inland Sea, Japan, and examined the relationship to their food availability. The survival rates were directly calculated from the change in larval density during the survey. The estimated daily survival rate ranged between 0 and 89% d⁻¹, but increased with the increase in the mean concentration of small‐sized copepod nauplii (<100 μm in body length) sampled at 10 m depth. When the food concentration was higher than about 5 nauplii L⁻¹, the daily survival rate of larval anchovy reached an asymptote of approximately 89% day⁻¹. It might be possible to provide a framework for the forecast for larval abundance immediately prior to recruitment size (10–15 mm SL), based on larval abundance of the monitored size (3–8 mm SL) and the survival rate which is estimated from the concentration of small‐sized nauplii.     

Growth, Maturation, Induced Spawning, and Production of the First Generation of South American Catfish, Pseudoplatystoma sp., in North America

Growth, plasma steroids, and the appearance of gonads (histology and gonadosomatic index) were followed in South American catfish (surubim, Pseudoplatystoma sp.) raised in captivity in the aquaculture facility at The Ohio State University, Columbus, Ohio, USA, from 2003 until 2006. Broodstock growth showed a great individual variation and it did not seem sex dependent. The levels of 11‐ketotestosterone were high in males during the reproductive season. Three out of six females spawned after receiving two doses of carp pituitary extract (0.5 and 5 mg/kg) at 11‐h intervals. Fertilization was performed in only one female in February 2006. Egg size was 0.73 ± 0.06 mm in diameter at stripping. Two males released sperm, and it was used for fertilization. Sperm concentrations were 24 × 10⁹ and 15.5 × 10⁹ spermatozoa/mL in Male 1 and Male 2, respectively, and viability was confirmed after activation in 0.3% NaCl. Embryo survival at 9 h after fertilization was 44 and 23% for Male 1 and Male 2, respectively. Embryos hatched 15 h after fertilization. Larvae were 3.53 ± 0.09 mm in length at hatching and were successfully raised (72% survival after 2 wks) using live brine shrimp nauplii.     

Effects of elevated pCO2 on the early development of the commercially important gastropod,Ezo abalone Haliotis discus hannai

We used an up‐to‐date, a high accuracy CO₂ manipulation system to investigate the sensitivity of organisms to CO₂ acidification, rearing marine calcifiers under elevated CO₂ in running water. We evaluated the effects of elevated partial pressures of carbon dioxide (pCO₂) in seawater on larvae of the commercially important marine gastropod Ezo abalone Haliotis discus hannai. In larval Ezo abalone, no effect of exposure to <1100 μatm pCO₂ seawater was observed in fertilization, malformation, or mortality rates until 15 h after fertilization. However, compared to control larvae in seawater (450 or 500 μatm pCO₂), the fertilization rate and the hatching rate (15 h after fertilization) decreased with increased pCO₂ exposure (1650 and 2150 μatm pCO₂) and the malformation rate increased significantly, with the larval shell length being smaller 75 h after hatching. These results suggest that ocean acidification will potentially impact the marine population of Ezo abalone as a human food source in the future.     

Cryopreservation of silver barb Puntius gonionotus (Bleeker) spermatozoa: effect of extender composition,cryoprotective agents and freezing rate on their postthawing fertilization ability

The effects of extender composition, cryoprotectant concentration and freezing and thawing on the fertilization efficiency of cryopreserved spermatozoa of Puntius gonionotus were evaluated. Computer‐aided motility analysis of semen was conducted to check the suitability of spermatozoa for cryopreservation after mixing with different extenders and cryoprotective agents (CPAs). Extender‐4 with an osmolality 260 mOsmol kg⁻¹and pH 7.6 was used for the cryopreservation study. Among the CPAs, dimethyl sulphoxide (DMSO) was least toxic and more than 60% fertilization was achieved when used at 1.4 M at 0 °C for 10 and 30 min, whereas the toxicity of all CPAs to spermatozoa was evident when tested at 30 °C. Semen frozen at −16 °C min⁻¹ with 1.4 M DMSO showed 70% fertilization, which was significantly higher (P<0.05) than other freezing rates. Samples thawed at 35 °C water showed a fertilization rate comparable with that of fresh semen. Computer‐assisted semen analysis of fresh and frozen semen after thawing showed variations in different types of motility in spermatozoa and in their class. There was no significant difference in motility before or after cryopreservation; however, significant differences could be observed in the average path velocity (VAP), straight line velocity (VSL) and curve linear velocity (VCL). Semen of silver barb could be cryopreserved with extender‐4 by addition of 1.4 M DMSO to a final cryopreservation medium (MED 2) cooled at a rate of −16 °C min⁻¹, stored in liquid nitrogen (−196 °C) and utilized after thawing at 35±2 °C.     

Effects of temperature and food availability on growth rate during late larval stage of Japanese anchovy (Engraulis japonicus) in the Kuroshio–Oyashio transition region

During periods when the population size of Japanese anchovy Engraulis japonicus is large, the abundance of 1‐yr olds has been considered to be dependent on the growth and survival processes in the late larval and early juvenile stages in the Kuroshio–Oyashio transition region off northern Japan. Recent growth rates for 10 days before capture of larval and early juvenile E. japonicus were estimated and examined in relation to the surface water temperature and the available copepod density in 1997, 1998 and 1999. Late larval and early juvenile E. japonicus were distributed in the waters with temperature from 15 to 19°C and available prey density from 10 to 1000 mg dry weight (DW) m^?2 in the transition region. The late larval growth rates were found to be regulated more strongly by water temperature than by copepod density in the waters <16°C, and more strongly by copepod density than water temperature in the waters <100 mg DW m^?2 in the Kuroshio–Oyashio transition region. The recent growth rates decreased from the western waters to the eastern waters in the survey area 140–170°E in 1998, correlating with decreases of food availability to 50–100 mg DW m^?2. While in 1999, the recent growth rates were faster in the waters east of 150°E, resulting from eastward expansion of warm water ranges and high available prey density 100–400 mg DW m^?2. The key environmental factors regulating late larval growth rate of E. japonicus in the transition region seem to be spatially different between years.     

An efficient method for cryopreservation of testicular sperm from the Northern pike, Esox lucius L.

The cryopreservation of semen from the Northern pike, Esox lucius L., was investigated with a method that was originally developed for the Salmonidae. Because the amounts of semen obtained by stripping were insufficient, the suitability of testicular sperm was tested for cryopreservation. Frozen-thawed testicular sperm had fertilization rates similar to frozen-thawed semen obtained by stripping (74.2-84.7%), and at sperm to egg ratios of S= 4.5 × 10⁵ spermatozoa per egg, the post-thaw fertilization rates were also similar to fresh, untreated semen controls. Out of all the fertilization solutions investigated, a 100-mm NaCl, 10-mm Tris (pH 9) solution resulted in the highest post-thaw fertilization rates. To facilitate the fertilization of large egg batches, 1.2-mL straws were used for cryopreservation with a similar efficiency to 0.5-mL straws.     

Improved hatchery‐rearing techniques for juvenile production of blue swimming crab,Portunus pelagicus (Linnaeus, 1758)

The effects of tank colour, larval stocking density, antibiotic administration and water exchange on survival and moulting of blue swimming crab, Portunus pelagicus, were determined. Circular 4‐m³ experimental larval‐rearing tanks were used in triplicate for all treatments. White, dark grey, blue and brown were tested as tank background colours. The stocking densities tested were 10, 20, 40, 60, 80 and 100 larvae L^?1. The effect of oxytetracycline was estimated by comparing a treatment with oxytetracycline to a treatment without oxytetracycline administration. The daily water exchange rates tested were 0%, 25%, 50% and 100% of the tank volume. In all treatments, the larvae were fed with Artemia nauplii, rotifers and encapsulated Spirulina. The highest percentage survival was observed in the dark‐grey tanks when the stocking density of larvae was 20 larvae L^?1. No larva reached the juvenile crab size in white tanks. No significant difference in survival was found between treated and non‐treated larvae with oxytetracycline when the daily water exchange rate was more than 50%.     

Optimization of fertilization rate for maximizing periphyton production on artificial substrates and the implications for periphyton-based aquaculture

The effects of four rates of application of fertilizer, with cow manure (3000 kg ha⁻¹), urea (100 (kg ha⁻¹) and triple super phosphate (TSP) (100 kg ha⁻¹) (treatment F)), treatment F × 0.5 (treatment 0.5F), treatment F × 1.5 (treatment 1.5F) and treatment F × 2 (treatment 2F), on periphyton, plankton and water quality in tropical freshwater ponds were studied. The highest periphyton biomass in terms of dry matter (3.27 mg cm⁻² substrate), ash-free dry matter (2.06 mg cm⁻² substrate) and chlorophyll a (7.49 µg cm⁻² substrate) developed in treatment 1.5F. The ash content of periphyton was lower in treatment 1.5F (38% of dry matter) than in other treatments (57–66% of dry matter). Total ammonia and chlorophyll a of water increased with fertilization rate. Treatment 1.5F (cow manure, urea and TSP at rates of 4500, 150 and 150 kg ha⁻¹ respectively) appears to be the optimum, yielding high quantity and quality periphyton. By supplying a substrate area for periphyton equivalent to the pond surface, it was estimated that this level of fertilization could support a fish production of around 5000 kg ha⁻¹ y⁻¹, without recourse to supplementary food.     

Combined effects of water temperature and daily food availability period on the growth and survival of tench (Tinca tinca) larvae

A 16‐day experiment was designed to find the best combination of water temperature (27, 30, 33°C) and daily duration of food availability (12, 18, 24 h) for larval tench (Tinca tinca) growth and survival. Larvae with an initial mean size of 5.7 mm total length (TL) and 0.7 mg wet body weight (BW) were stocked at 15 L^?1. Larvae were fed in excess with live Artemia nauplii with the period of food availability lasting 12, 18 or 24 h daily. The largest final larval size was recorded at 27 and 30°C in groups fed for 24 h a day (17.7 and 17.9 mm TL, 76.1 and 77.7 mg BW, respectively). The combination of the highest temperature and the longest daily food availability was the only set of conditions under which final larval survival was affected (95.4% survival; 98.7–99.9% under all other conditions). The combination of water temperature of about 28.6°C and continuous food availability is recommended as the optimum combination for rearing T. tinca larvae under controlled conditions. Providing continuous food supply to fish larvae under aquaculture conditions was also advantageous in helping to mitigate the effects of slower growth relative to developmental progress, which can occur at high water temperatures. However, should one wish to limit the daily feeding period to 12 h per day, the use of a water temperature between 27.4 and 27.9°C would be the best solution.     

Effects of ultra-violet irradiation on sperm motility and diploid gynogenesis induction in large yellow croaker (<Emphasis Type="Italic">Pseudosciaena crocea</Emphasis>) undergoing cold shock

Large yellow croaker, Pseudosciaena crocea, exhibit sexually dimorphic growth, with females growing faster and reaching larger adult sizes than males. Thus, development of techniques for preferentially producing females is necessary to optimize production of these species. We have established a protocol to produce all-female croaker P. crocea through induction of meiotic gynogenesis with homologous sperm. The first set of experiments investigated the ultra-violet (UV) irradiation on sperm motility and duration of sperm activity to determine the optimal UV dosage for genetic inactivation of sperm, yet retaining adequate motility for activation of eggs. Milt from several males was diluted 1:100 with Ringer’s solution and UV irradiated with doses ranging from 0–150 J cm⁻². The results indicated that motility and duration of activity generally decreased with increased UV doses. At UV doses greater than 105 J cm⁻², after fertilization, motility was <10% and fertilization rates were significantly lower. Highest hatching rate was obtained at 75 J cm⁻². A second set of experiments was carried out to determine appropriate conditions of cold shock for retention of the 2nd polar body in P. crocea eggs after fertilization with UV-inactivated sperm by altering the timing, temperature and duration of shock. At 20°C, shock applied at 3 min after fertilization resulted in higher survival rate of larvae at 6 h after hatching. Results of different combinations of three shock temperatures (2°C, 3°C or 4°C) and five shock durations (4 min, 8 min, 12 min, 16 min or 20 min) at 3 min after fertilization demonstrated that shocks of 12 min gave highest production of diploid gynogens. Statistical analysis revealed that maximum production of diploid gynogens (44.55 ± 2.99%) were obtained at 3°C. The results of this study indicate that the use of UV-irradiated homologous sperm for activation of P. crocea eggs and cold shock for polar body retention is an effective method for producing gynogenetic offspring.     

Improvement of common carp artificial reproduction using enzyme for elimination of egg stickiness

This study summarizes optimization of techniques for common carp artificial propagation including improvements of activation solution (AS), the process of insemination, and elimination of egg stickiness. The optimum gamete ratio for good fertilization and hatching rate ranged from 8490 to 23 672 spermatozoa per egg, when dechlorinated tap water was used. Optimal ratio between eggs (weight in g) and AS (in ml) was defined as 1:1 to 1:2. Different concentrations of AS such as NaCl from 0 to 34 mM (0–68 mOsmol kg^–1) did not change fertilization and hatching rates. An AS adopted for carp spermatozoa (45 mM NaCl, 5 mM KCl, 30 mM Tris–HCl, pH 8) was compared with other saline AS; only the 51 mM (102 mOsmol kg^–1) NaCl solution decreased fertilization and hatching rate. The AS containing 20 mM Tris–HCl at pH 9 increased fertilization and hatching rates compared to dechlorinated tap water of pH 7 or to AS of pH 6 and 7. Adhesiveness from the eggs was successfully removed by incubation in Alcalase DX (PLN 04715) using two successive steps with different enzyme concentrations. The first step with an enzyme concentration of 2 ml l^–1 was applied from 8 to 20 min after fertilization. Later in a second step, the best time for application of alcalase enzyme at a concentration of 20 ml l^–1 was for 45 and 60 s at 20 min after fertilization leading to fertilization and hatching rates of 80–87%. The α-Chymotrypsin (EC 3.4.21.1. Merck) was also found effective for elimination of stickiness. Results with α-Chymotrypsin enzyme indicate that the response to success in elimination of stickiness is highly variable mainly due to differences in the environment, quality of water and carp strains.     

Effect of extenders on sperm cryopreservation of African catfish, Clarias gariepinus (Burchell)

The effect of extenders was studied on the cryopreservation of sperm from African catfish, Clarias gariepinus (Burchell). The following six basic extenders were tested: fructose, glucose, sucrose, NaCl, KCl solutions and the artificial seminal plasma of the African catfish. Each of these extenders was tested both with and without buffer systems (i.e. NaHCO₃-CO₂ and Tris-HCl) by using 10% dimethyl-sulphoxide (DMSO) as a cryoprotectant. The two-step freezing was carried out in a programmable freezer by using the following freezing rates: (1) 4 °C min^–1 between 3 and –4 °C; (2) and 11 °C min^–1 between –4 and –80 °C. The best post-thaw motility (25%) was achieved with 333 mmol L^–1 fructose solution and NaHCO₃ buffer. The fertilization experiments were carried out with unbuffered fructose and glucose extenders using various amounts of sperm and two fertilization methods: (1) dry and (2) wet. The best fertilization rates were achieved with 75 μL of sperm and wet fertilization with glucose extender, or 100 μL of sperm and dry fertilization in case of fructose – both methods fertilized 96% of all eggs.     

Evaluation of egg quality in broodstock cobia Rachycentron canadum L.

Twenty egg batches spawned naturally from 17 different females over two spawning seasons were used to evaluate the egg quality of cobia Rachycentron canadum. A reduction in egg size was observed towards the end of the spawning season for both years. The proportion of floating eggs demonstrated a positive linear relationship with both yolk‐sac larval survival (r²=0.91, P<0.05) and batch larval production (r²=0.80, P<0.01). Viable egg batches (i.e. fertilization success >50%) were of higher batch fecundity, had larger eggs and a higher proportion of floating eggs than non‐viable batches (i.e. 0% fertilization success). Also, biochemical analyses revealed that these viable eggs had significantly higher protein and amino acid contents. A multiple regression model based on the proportion of floating eggs, batch fecundity and fertilization success provided the most accurate predictions of batch larval production (r²=0.95, P<0.001). Similarly, using the egg content of arginine/glycine and methionine significantly increased the correlation coefficient in the multiple regression model predicting larval deformity (r²=0.92, P=0.002). This study reveals that accurate determination of egg quality in cobia can be improved using a combination of several variables rather than a single variable.     

Breeding and larval rearing of the camouflage grouper Epinephelus polyphekadion (Bleeker) in the hypersaline waters of the Red Sea coast of Saudi Arabia

This is the first report on the successful year-round natural spawning and larval rearing of Epinephelus polyphekadion (Bleeker) in captivity and under hypersaline water conditions of 42-43%₀ salinity in the Red Sea coast of Saudi Arabia. Although the fish spawned naturally once or twice a year during 1992-94 culture period, incorporation of cod-liver oil in the broodstock diet during the 1995 culture period enabled the fish to spawn continuously for 2-3 days in each month during March, April, May and August. The egg fertilization and hatching rates also increased during the 1995 spawning period. The egg fertilization rate varied from 90 to 100% with a mean of 96.5 ± 3.38%. The egg hatching rate varied from 70 to 95% with a mean of 83.1 ± 10.12%. The fertilized egg diameter averaged 757.3 ± 37.36 μm. There was a linear relation between the fertilized egg size and the egg hatching rate. The increase in the hatching rate relevant to the egg size was statistically significant (P < 0.01). The egg development time until hatching lasted for 19 h at 29°C. The newly hatched larval size ranged from 1.55-1.71 mm with a mean of 1.65 ± 0.052 mm in total length. The larval growth was slow in the early stages and the growth curve until metamorphosis showed a curvilinear pattern. Wide variations in larval size, range 22-47 mm with a mean of 33.40 ± 7.01 mm, were observed during the metamorphosis stage at day 50. No significant difference (P > 0.05) in growth and survival was observed between the larvae reared using white and grey coloured tanks. The larval survival up to metamorphosis was 1.6-4.7% with a mean of 2.98 ± 1.56% in the grey coloured tanks and 1.6-1.9% with a mean of 1.73 ± 0.16% in the white tanks. The results demonstrated the possibility of breeding E. polyphekadion under captive culture conditions. However, methods to improve the larval survival have to be pursued further for commercial farming of this species.     

Larval rearing of African carp,Labeo parvus Boulenger, 1902 (Pisces: Cyprinidae), using live food and artificial diet under controlled conditions

This study aimed at (1) evaluating the efficacy of live food organisms (Artemia and natural zooplankton) and an artificial diet in the larval rearing of African carp Labeo parvus and (2) determining appropriate rearing conditions. After yolk sac resorption, the larvae were separated into five different feeding trials with two replicates. At the end of the larval rearing period (28 days post‐hatching), the highest (94.6%) and the lowest (53.7%) cumulative survival rates were found when larvae were fed with natural zooplankton for 7 days followed by Nippai food for 21 days, and when larvae were fed from the beginning of exogenous feeding with Nippai food only respectively. The significant highest body weight (351.6 mg), total length (34.4 mm) and specific growth rates (15.5%day^?1) were recorded when the larvae were fed with Artemia nauplii for 14 days followed by Nippai food for 14 days. The lowest growth performance (body weight and specific growth rates) were obtained when larvae were fed exclusively Nippai food. These results indicate that L. parvus can be successfully cultured in indoor nursery systems from hatching to the early juvenile stage.     

Captive Breeding of Endangered Ompok pabda with Ovatide

The Pabdah catfish, Ompok pabda, was successfully spawned with the synthetic hormone Ovatide at two different doses (0.4 and 0.6 ml/kg of body weight of female). The latency period was 9–10 h at 0.6 ml compared to 10–12 h at 0.4 ml kg^?1 of body weight. All the females spawned successfully. Average rate of fertilization (75.5 %) and hatching (60.5%) was higher with a dose of 0.6 ml kg^?1, while lower fertilization (65.1%) and hatching rate (45%) were observed at 0.3 ml kg^?1 of body weight. Fecundity ranged from 80–130 eggs gm^?1 body weight of female. Eggs hatched between 12–14 h after spawning at a water temperature 28°–32°C. The mean egg diameter was 0.95 ± 0.15 mm.