Food and feeding habits of Tilapia aurea (Steindachner) (Cichlidae) in Lake Kinneret (Israel)

An analysis of the food of 274 specimens of Tilapia aurea (Steindachner), which had been collected in Lake Kinneret, showed that this species is mainly a zooplankton consumer.A study of the quantitative dynamics of the food components in the course of a year has proved that the species in question feeds more intensely in spring, this being the time when zooplankton forms are more abundant in the water of the lake. Vegetable detritus, mixed with plankton and benthos forms, served as additional and alternative food.The lack of clearly positive degree of food component selectivity, as well as the low values of the intestine repletion index and of the condition coefficient, account for the slowness in growth of Tilapia aurea in Lake Kinneret.The low values of the growth and feeding indices are due, according to the authors, to the pressure brought to bear by the other local fish species, which are competitors for the same food.     

Food and feeding habits of Tilapia zillii (Gervais) (Cichlidae) in Lake Kinneret (Israel)

Analysis of the gut content of 329 specimens of T. zillii (Cichlidae) collected from Lake Kinneret, has shown great variation in the sorts of food.A study of seasonal dynamics has proved the prevalence in the food of Chironomida pupae (Diptera) in winter and spring and of zooplankton forms in summer and autumn. The additional food consisted of the various groups of algae, the most frequently found being Cyanophyta (100%) and Pyrrophyta (64.16%). An extremely voraceous species, it consumes — while searching for its preferred food — anything that comes its way in the water: algae, scraps of macrophytes, autochthonous and allochthonous insects, and forms of benthic origin, such as Nematoda, Ostracoda, Porifera and Chironomida (larvae).The satiation index is high (between 4.08 and 5.63), in contradiction to the low values of the coefficient of condition (between 3.05 and 3.51), and with the slow rate of growth in Lake Kinneret. The main food of Tilapia zillii, consists of arthropod species with a chitin content (which is eliminated unchanged) of more than 50% of the total weight, and this may account for the poor exploitation of the trophic base.This species of fish may be considered as being detrimental to others (i.e. commercially important species) because of its successful competition for food, and not, as is often incorrectly assumed, because it is an aggressive consumer of their spawn and fry.     

不同品系尼罗罗非鱼致死低温的研究

在室内自然降温条件下，研究了三个品系尼罗罗非鱼（吉富品系，“７８”品系，“８８”品系）对低温的耐受力，计算得出每个品系的半致死低温，并对降温过程中尼罗罗非鱼行为活动的变化进行了观察。试验结果表明，在上海地区，当温度降低到１１℃时，罗非鱼开始死亡，到７．４℃时，全部死亡。吉富罗非鱼死亡温度范围是１１℃￣８．４℃，“７８”品系是９．８￣７．４℃，“８８”品系是１１℃￣７．４℃。对三个品系半致死低温的研     

Grass carp (Ctenopharyngodon idella) grazing on duckweed (Spirodela polyrhiza)

The aims of this experiment were (1) toquantify the ability of grass carp to processduckweed and (2) to assess indirect changes inwater chemistry and phytoplankton community,caused by grass carp feeding. Yearling grass carp sized 126 ± 7.7 mm (TL) and19.6 g in weight were kept in 9 laminate tanksof 1 m³ for 14 days. Two stockingdensities (2 and 6 fish per m³) anda control without fish were used. Standard growthrate (SGR) of grass carp fed exclusively onduckweed was 0.70% body weight (BW) d^–1and food conversion ratio (FCR) reached 2.0(average water temperature =21.1 ± 3.8 °C). Daily food intakewas 0.2 g of duckweed dry weight (DW), i.e.,1% of average BW of grass carp. SGR ofduckweed growing in 20 × 20 cm floatingenclosures, differed significantly[F(6,2) = 417.9; p = 0.002] between the twostocking densities of grass carp and thecontrol tanks (without fish). Mean SGR ofduckweed was 0.02 g g^–1 day^–1 and thehighest SGR was recorded in the control tanks.Both decrease in NH₄-N and increase inNO₂-N concentrations differedsignificantly between the treatments[F(2,2) = 45.3; p = 0.02 and F(2,2) = 19.2; p = 0.04 respectively]. Changes in other nitrogenand phosphorus components (NO₃-N, TN, TPand PO₄-P) caused by stocking of grasscarp were not significant. Biomass ofphytoplankton, dominated by filamentous algaeand blue-greens, increased proportionately tostocking density of grass carp. Althoughduckweed has a large potential for nutrientremoval, the most common pathway for thenutrients released through grass carp grazingif duckweed cover is loose is theirincorporation into phytoplankton biomass.     

叶尔羌高原鳅胚胎发育与胚后发育观察

采用形态学和生态学方法,对叶尔羌高原鳅[Triplophysa(Hedinichthys)yarkandensis(Day)]胚胎发育和胚后发育阶段全过程进行观察、拍照并测量。结果显示:叶尔羌高原鳅,卵微黏性,略有沉性,受精卵呈卵圆形,卵径为(0.60±0.052)mm,在水温(20.0±1.0)℃下,历时65 h 34 min完成整个胚胎发育分为7个生理阶段过程;胚后发育主要根据卵黄囊、体色、鼓鳔和须的变化分为仔鱼期、稚鱼期、幼鱼期。初孵卵黄囊仔鱼全长(2.0±0.65)mm,出膜后7 d,卵黄囊吸收完毕,完全消失;初孵仔鱼继续培育至16日龄,仔鱼鳃盖后缘鼓鳔明显长出,须清晰可辨,体色加深,心脏红色素明显,体色与成体相似,标志后期仔鱼发育完全进入稚鱼期,此时鱼苗全长(8.0±0.45)mm;培育至30日龄,仔鱼鼓鳔完全,鳃盖张合明显,身体透明特征消失,稚鱼阶段完成发育进入幼鱼期,此时全长达(13.0±0.55)mm,其外部形态和生态习性均与成鱼相似。试验中,卵黄囊长度(LY)和出膜天数(D)的关系式:LY=0.0286D2–0.0636D+3.1196(R2=0.9050);用直线方程拟合卵黄囊长度(LY)和卵黄囊仔鱼全长(LT)的关系式:LY=–1.315LT+5.368(R2=0.8199);拟合卵黄囊仔鱼全长(LT)和出膜后仔稚鱼天数(D)的关系式:LT=–0.0263D2+0.5113D+1.6169(R2=0.9890)。本研究旨在通过了解叶尔羌高原鳅的早期发育特征为该物种的保护和增殖对策提供科学依据,并对其苗种生产提供理论指导。     

Extinction of Daphnia lumholtzi (Sars) in Lake Kinneret (Israel)

Daphnia lumholtzi (Sars) was found in Lake Kinneret until the late nineteen-fifties. Lake Kinneret was the northern-most limit of the distribution of this species. It is suggested that fingerlings of grey mullets and Sarotherodon aureus that were introduced into Lake Kinneret caused the extinction of D. lumholtzi.     

Development of embryos in Mastacembelus mastacembelus (Bank & Solender, 1794) (Mesopotamian spiny eel) (Mastacembelidae)

In this study, the embryonic development of the eggs in the Mastacembelus mastacembelus (Bank & Solender, 1794) was examined. At the same time, possibilities of artificial breeding through artificial insemination were investigated. Artificial insemination was achieved by mixing the eggs of the mature female and sperm of the mature male samples caught with gill nets (22 × 22) in Ataturk Dam Lake in Turkey. To this end, first in a Petri dish (100 × 20), the testes were cut into small pieces with a lancet and the mixture of sperm–testes‐tissue was obtained. The fertilization rate of the eggs was found to be 80%. The diameter of the eggs ranged from 2.015to 1.147 mm. The perivitelline space formed 0.5 h after insemination. The first cleavage occurred at the animal pool 4 h after insemination. The oil droplets had fused to a single droplet 19 h after insemination. The blastoderm became an embryonic shield 30 h after insemination. The blastoderm covered almost half the egg 40 h after insemination and embryonic body was formed. The blastoderm covered almost the whole egg 50 h after insemination. Some somites were discernible 59 h after insemination. The embryonic body reached two‐third of the circumference of the egg 70 h after insemination. The tail bud began to separate from the yolk 77 h after insemination. A newly hatched larva was observed at 85 h after insemination.     

Transmission of white spot syndrome virus (WSSV) from Dendronereis spp. (Peters) (Nereididae) to penaeid shrimp

Dendronereis spp. (Peters) (Nereididae) is a common polychaete in shrimp ponds built on intertidal land and is natural food for shrimp in traditionally managed ponds in Indonesia. White spot syndrome virus (WSSV), an important viral pathogen of the shrimp, can replicate in this polychaete (Desrina et al. 2013); therefore, it is a potential propagative vector for virus transmission. The major aim of this study was to determine whether WSSV can be transmitted from naturally infected Dendronereis spp. to specific pathogen‐free (SPF) Pacific white shrimp Litopenaeus vannamei (Boone) through feeding. WSSV was detected in naturally infected Dendronereis spp. and Penaeus monodon Fabricius from a traditional shrimp pond, and the positive animals were used in the current experiment. WSSV‐infected Dendronereis spp. and P. monodon in a pond had a point prevalence of 90% and 80%, respectively, as measured by PCR. WSSV was detected in the head, gills, blood and mid‐body of Dendronereis spp. WSSV from naturally infected Dendronereis spp was transmitted to SPF L. vannamei and subsequently from this shrimp to new naïve‐SPF L. vannamei to cause transient infection. Our findings support the contention that Dendronereis spp, upon feeding, can be a source of WSSV infection of shrimp in ponds.     

褐牙鲆(♀)×犬齿牙鲆(♂)杂交F1及其亲本肌肉营养成分分析与比较

褐牙鲆(Paralichthys olivaceus)为东亚地区重要的海水养殖鱼类,在中国、日本和韩国海水养殖业中占有重要的地位.目前,褐牙鲆经过连续多代缺乏选择的人工繁育和养殖,造成养殖群体种质发生退化,生长速度和抗逆性下降,极大制约了牙鲆养殖业发展.以选育生长迅速、抗逆性强、饵料转化率高的牙鲆类养殖新品种为目的,作者对褐牙鲆(♀)×犬齿牙鲆(Paralichthys dentatus)(♂)的杂交育种进行了研究.本实验对褐牙鲆(♀)×犬齿牙鲆(♂)杂交F1及其亲本肌肉营养成分进行测定.结果显示,杂交F1含水率显著低于双亲(P＜0.05),粗蛋白含量显著高于双亲(P＜0.05),粗脂肪含量介于二者之间;杂交F1的氨基酸总量、必需氨基酸、非必需氨基酸、半必需氨基酸与鲜味氨基酸总量都显著高于褐牙鲆与犬齿牙鲆(P＜0.05);脂肪酸含量方面,脂肪酸总量、不饱和脂肪酸总量3种鱼由高到低排列顺序为褐牙鲆、犬齿牙鲆、杂交F1,三者饱和脂肪酸总量差异不显著(P＜0.05).对3种鱼肌肉的营养品质进行了评价,杂交F1的必需氨基酸指数EAAI(90.30)明显高于褐牙鲆(77.75)与犬齿牙鲆(79.34),在蛋白质品质上表现出一定杂种优势.上述结果表明,杂交F1的肌肉具有蛋白和氨基酸含量较高、脂肪酸含量较低的特点.     

Substitution effect of sea tangle (ST) (Laminaria japonica) with tunic of sea squirt (SS) (Halocynthia roretzi) in diet on growth and carcass composition of juvenile abalone (Haliotis discus,Reeve 1846)

Substitution effect of sea tangle (ST) with tunic of sea squirt (SS) in diet on growth and carcass composition of juvenile abalone was determined. One thousand four hundred and seventy abalones were distributed into 21 containers. Six formulated diets in triplicate were prepared. A 200 g/kg ST was included into the ST0 diet. The 200, 400, 600, 800 and 1000 g/kg of ST were substituted with the same amount of tunic of SS, referred to as the ST200, ST400, ST600, ST800 and ST1000 diets, respectively. Finally, Undaria was prepared to compare effect of the formulated diets on performance of abalone. The experimental diets were fed to abalone for 16 weeks. Weight gain of abalone fed the ST400 diet was higher than that of abalone fed the ST0, ST600, ST800 and ST1000 diets and Undaria. Weight gain of abalone fed the formulated diets was higher than that of abalone fed the Undaria. The chemical composition of the carcass of abalone was affected by dietary substitution of ST with tunic of SS. In conclusion, ST could be completely substituted with tunic of SS without retardation in performance of abalone. Abalone fed the ST400 diet substituting 400 g/kg ST with tunic of SS achieved the best growth.     

Ontogenetic changes in the diet of the black-stripe minnow Galaxiella nigrostriata (Shipway, 1953) (Galaxiidae) and the salamanderfish Lepidogalaxias salamandroides (Mees, 1961) (Lepidogalaxiidae)

Abstract –  Similarities in the diets of larval, juvenile and adult black-stripe minnow ( Galaxiella nigrostriata ) and salamanderfish ( Lepidogalaxias salamandroides ), collected from ephemeral pools in south-western Australia during the mid-wet, late-wet and dry seasons, were assessed. During the mid-wet season, both intra- and interspecific competition for a diminishing food supply was minimised through differences in prey utilisation by the various developmental stages of both species. During the late-wet season, the pools contained only juvenile G. nigrostriata and juvenile and adult L. salamandroides , the diets of which were vastly different. A shift towards terrestrial fauna by G. nigrostriata and the ingestion of greater proportions of larger benthic prey taxa by L. salamandroides minimised interspecific competition for food at a time when densities of zooplanktors were rapidly declining. Timing differences in the onset of aestivation ensures that no interspecific competition for food occurs during the dry season.     

Goussia auxidis (Dogiel, 1948) (Apicomplexa: Calyptosporidae) from tuna (Pisces: Scombridae) in the South Pacific

Abstract. A coccidian identified as Goussia auxidis (Dogiel, 1948) is recorded for the first time from the liver and spleen of albacore, Thunnus alalunga; the liver of slender tuna, Allothunnus fallai , skipjack tuna, Katsuwonus pelamis and yellowfin tuna, T. albacares: and in the spleen of Scomber australasicus. All host fish were caught in the western and central South Pacific Ocean. Coccidian spores were not found in the liver of southern bluefin tuna, T. maccoyii , or butterfly tuna, Gasterochisma melampus.     

日本蟳幼体发育的研究

日本蟳Charybdis(charybdis)Japonica(A.Milne-Edwards)是我国大型海产食用蟹类之一。它遍布我国、日本、朝鲜和马来西亚沿岸,红海等亦有分布。关于日本蟳幼体发育的研究,Aikawa(1937)曾观察了第1期溞状幼体,Kurata和Nishina(1975)观察到第4期溞状幼体;八塚刚(1952、1957、1962)和寺田正之(1979)也曾对日本蟳的溞状幼体进行过描述,而我国沿海日本蟳发育,迄今未见研究报告。笔者自1984年7月,开始了日本蟳的室内人工繁殖和幼体培育,并培养出第1期幼蟹,85年又对各期幼体的发育形态进行了系统的观察和研究。现将结果整理如下。     

Complete developmental cycle of Myxobolus pseudodispar (Gorbunova) (Myxosporea: Myxobolidae)

Myxobolus pseudodispar (Gorbunova) is a common parasite of the muscle of roach, Rutilus rutilus L., whereas its actinosporean development occurs in two oligochaete alternate hosts. This paper reports the complete developmental cycle of this parasite in the oligochaete alternate host Tubifex tubifex and the roach. In laboratory experiments, parasite-free T. tubifex specimens were infected by myxospores of M. pseudodispar collected from roach in Lake Balaton. Parasite-free roach fingerlings were infected with floating triactinospores (TAMs) released from oligochaetes on day 69 after challenge. Young plasmodia and spores in roach were first recorded on day 80 post-exposure (p.e.). Myxospores collected from experimentally infected roach initiated a new development in T. tubifex and the resulting TAMs infected roach. No infection of roach resulted from feeding oligochaetes containing mature triactinospores.     

中华倒刺（鱼巴）人工繁殖试验

中华倒刺鱼巴Barbodes (Spinibarbus) sinensis (Bleeker),地方名青波、青板、乌鳞,以肉质细嫩、肉味鲜美为人们所喜食,具有生长快、个体大、食性广、耐低氧、抗病力强、经济效益高等特点,深受养殖户的青睐.近年来,由于江河野生资源日益枯竭,市价居高不下,一些养殖单位都竞相饲养,但种苗的数量受到限制,仅从江河捕捞的鱼苗根本不能满足成鱼规模养殖所需.开展中华倒刺鱼巴的人工繁殖,对渔业生产的发展具有重要的现实意义.     

塔里木河流域叶尔羌高原鳅的生态学研究

塔里木河流域叶尔羌高原鳅是偏肉食的杂食性鱼类。喜夜间活动觅食,生存的最低临界温度为5℃,最高临界温度为33℃,适宜水温在19℃。有弱趋光性。溶氧低于2 mg/L时活动不正常,水体温度在20℃时,叶尔羌高原鳅的时窒息点为1.18 mg/L。     

4种药物对叶尔羌高原鳅的急性毒性试验

在水温(17±2)℃条件下,采用水生生物急性毒性试验方法,研究了福尔马林、高锰酸钾、硫酸铜和敌百虫,4种药物对叶尔羌高原鳅的24h、48h的半致死浓度(LD50)和安全浓度(SC)。结果表明:福尔马林、高锰酸钾、硫酸铜和敌百虫24h的LC50分别为:113.89、6.43、3.37和14.18mg/L。48h的LC50分别为97.03、4.50、2.38和11.28mg/L。4种药物的SC分别为24.08、0.94、0.50和2.69mg/L。在对叶尔羌高原鳅疾病预防和治疗过程中,建议高锰酸钾不要用于疾病的治疗,硫酸铜的使用要谨慎,福尔马林和敌百虫可用于疾病的治疗。     

鲐鱼

<正> 鲐鱼属鲈形目、鲭科、鲐鱼属。俗称青占,油筒鱼(上海、江苏、浙江);青花鱼,鲐巴鱼(辽宁、山东);花鳀(福建);花鲛(广东、海南)等。体呈纺锤形,粗壮稍侧扁;尾柄细短,尾基每侧有两条小隆起嵴。头中大,呈圆锥