淡水黑鲷池塘养殖试验

我们于2006年实施了淡水黑鲷(图见彩中插2)池塘养殖试验,取得了较好效果,现将情况总结如下:一、池塘条件试验地点在邹城市城前镇洼陡水库渔场7#、8#池,面积分别为1.2亩、1.8亩,平均水深1.8米,生产基地于2005年2月通过了无公害水产品产地认定。pH7.2～8.0之间,水质清新,溶氧充足,池塘排列整齐,底质为沙壤土,淤泥30厘米。并可借助地势自流排灌,适宜进行养殖生产。     

虱目鱼池塘养殖技术

虱目鱼(Chanos chanos Forskal)是虱目鱼科中唯一现存种,俗称麻虱鱼、塞目鱼、海草鱼等。虱目鱼属广盐性热带鱼类,可生活于淡水中,最适宜生长盐度为12-30。生活适温为16-39℃,水温降至15℃时其活动能力变弱,低于9℃时数分钟内死亡。虱目鱼运动活泼,性喜群游,是以植物为主的杂食性鱼类,可以投喂配合饲料。养殖方式主要有粗放式养殖和精养。北方地区养     

淡水石斑鱼池塘高产养殖试验

淡水石斑鱼(Cichlasomaman鄄aguense)为慈鲷科鱼类,原产于中美洲尼加拉瓜,是尼加拉瓜的主要淡水经济鱼类,具有生长快、抗病力强、易捕捞、肉质鲜美等特点。为了探索该鱼的养殖技术,我们于2002~2003年开展了淡水石斑鱼池塘高产养殖试验,经过两年的试验取得了较好的经济效益,现将     

北方地区淡水白鲳养殖试验

淡水白鲳原产南美洲亚马逊河，属热带与亚热带鱼类。生活适宜水温范围１２～３５℃，生长水温２１～３２℃，低温临界水温１０℃，７℃时死亡。具有生长快，抗病力强和易养殖垂钓，能忍受０．５毫克／升的低氧等特点。适宜在有一定肥度的池水中养殖。该品种１９９０年引入黑龙江，１９９４年开始在常规池塘试养，为进一步研究淡水白鲳在北方高寒地区常温下利用普通池塘养殖的可行性。我们于１９９７～２０００年之间进行了养殖试验，取得了较高的经济效益。现将试验情况报告如下：一、材料方法１．池塘水质试验池塘选择面积为６～１６亩的４…     

淡水白鲳池塘养殖试验

淡水白鲳属热带鱼类,具有生长快、食性广、病害少、耐低氧、味鲜美,并具药用价值等特点。２００１年作者进行了淡水白鲳夏花当年养成商品鱼试验,现将试验情况介绍如下:     

池塘网箱养殖淡水黑鲷鱼种试验

淡水黑鲷学名厚唇弱棘蜊（Hephaestus　fuliginosus），隶属于鲈形目，蜊科，弱棘蜊属，分布于澳大利亚北部沿海地带塔利河水系，是世界少有的分布在淡水中的鲷科鱼类，其生存温度为12～34℃，摄食温度为15～32℃，最适生长温度为22～27℃，是近年来在原产国迅速发展起来的新兴的优良淡水养殖品种。淡水黑鲷体态丰腴，色泽华丽，肉质细腻，无泥腥味，具有生长速度快，食性杂，     

北方地区淡水鲨鱼池塘养殖试验

为了能在北方地区自然条件下大面积推广养殖淡水鲨鱼,我们于2004年在池塘进行淡水鲨鱼养殖试验,取得了较好的成效。现将试验情况总结如下:一、材料和方法1.清塘试验池4个,总面积5.2亩,水深1.5～2米,经过一个冬天的曝晒,在鱼种放养前10天用生石灰全池均匀泼洒,用量为75千克/亩。     

池塘培育淡水白鲳鱼种的试验

<正> 淡水白鲳(Colossoma brachypomum)是我国近年新引进的优良养殖品种,在我省已试养成功并取得较好的养殖效益,但白鲳鱼种的培育成活率仅在30％左右,随着推广面积的增加,淡水白鲳鱼种的供求矛盾日益突出。为提高淡水白鲳苗种的培育成活率,满足大面积推广的需求,而进行了提高培育成活率的试验。在淡水白鲳鱼苗的培育方面,国内仅见零星的资料。本文旨在探讨淡水白鲳     

虱目鱼的生物学特性及养殖技术

<正> 虱目鱼(Chanos chanos)俗称麻虱鱼、遮目鱼、海草鱼等,属鲱形目,遮目鱼科,遮目鱼属,是一种广盐性热带鱼类,广泛分布于印度洋和太平洋的热带及亚热带近海与内湾河口,我国主要分布于台湾沿海、南海及东海南部。虱目鱼肉味鲜美,生长迅速,病害少,是一个较优良的养殖品种。在台湾已有三百多年的养殖历史,近年来海南、广东等地开始推广养殖。我们于2002年从海南引进该品种5万尾,进行试验养殖,获得成功,现将其生物学特性和养殖技术简要介绍如下:     

细基江蓠繁枝变种与遮目鱼的混养试验

细基江蓠繁枝变种 (GracilariatenuistipitataV .liui)俗称细江蓠 ,在我国主要分布在海南岛 ,也是海南省海藻栽培的重要品种 ,细江蓠生长快 ,产量高。遮目鱼 [ChanosChanos(Forstal) ],生长迅速、饵料易得 ,鱼苗病害较少 ,易于饲养 ,是咸淡水养殖的重要对象。关于细江蓠与遮目鱼的混养迄今尚未见报道。 2 0 0 1～ 2 0 0 2年我们在兴发养殖场进行了细江蓠与遮目鱼混养的探索性试验 ,现将其初步结果总结如下。1　材料与方法1 .1　池塘条件　池塘面积 0 .2ha,池深 1 .2m ,底质为泥砂底 ,池端设有一进排水闸门 ,有海淡水水源。1 .2　清塘放苗…     

Polyculture of milkfish Chanos chanos (Forsskal) and the red seaweed Gracilariopsis bailinae (Zhang et Xia) in brackish water earthen ponds

Growth, net production, and survival rates of milkfish cultured with Gracilariopsis bailinae at two stocking density combinations (T₁– 30 fingerlings 100‐m^?2 pond+1‐kg G. bailinae 4‐m^?2 net cage, T₂– 30 fingerlings 100‐m^?2 pond+2‐kg G. bailinae 4‐m^?2 net cage) in brackish water earthen ponds over four culture periods were determined. The control (T₃) was stocked at 30 fingerlings 100‐m^?2 pond. Specific growth and production rates of G. bailinae were also calculated. There were no significant differences in mean growth, survival, and net production rates of milkfish between the three treatments. Irrespective of stocking singly or in combination with G. bailinae, significantly higher mean growth and mean production rates for milkfish were obtained during the third culture period of year 1 than those obtained from the other culture periods. Survival rates were not significantly different among the four culture periods. There were no significant differences in mean specific growth and mean net production rates between the two stocking densities of G. bailinae. Significantly higher mean specific growth and mean net production rates of red seaweed were also obtained during the third culture period of year 1 than those obtained from other culture periods. The production of milkfish and red seaweed was higher during the dry season. Growth rates of milkfish was positively correlated with temperature and salinity, while net production rates were positively correlated with temperature and total rainfall, but was inversely correlated with dissolved oxygen. G. bailinae growth and net production rates were positively correlated with water temperature and salinity. Results show that milkfish can be polycultured with G. bailinae grown in net cages in brackish water ponds at stocking density combination of 30 fingerlings 100‐m^?2 pond+1‐kg G. bailinae 4‐m^?2 net cage.     

Economics of milkfish (Chanos chanos) production in Hawaii*

Abstract

Economic evaluations of commercial milkfish (Chanos chanos) growout systems were made based on current Hawaiian fishpond, pond and tank culture techniques in Hawaii. Based on the observed practices of milkfish culture as a secondary or tertiary crop, capital costs and several operating costs were pro‐rated to accurately depict current farm practices. For a target harvest weight of 0.80 lb, the study estimates the total production cost for milkfish production at $3.31/lb for the pond system, $3.81/lb for the tank system and $1.84/lb for the Hawaiian fishpond system. At a sale price of $3.00/lb and seed cost of $0.25/fingerling, only the Hawaiian fishpond system is profitable under a 20‐year project life. When considering variable costs alone, the production cost is $1.78/lb for the pond system, $2.33/lb for the tank system and $1.53 for the Hawaiian fishpond system, yielding returns on variable costs of 67%, 30% and 59% respectively. Analyses of profit sensitivity to sale price, production yield, labor, feed and stocking indicate that sale price, as expected, has the largest impact on profitability, followed by feed. The results of this study are consistent with the Hawaii farmers’ view of milkfish as a secondary specie to core production based upon current market conditions and input requirements.     

Requirement for tryptophan by milkfish (Chanos chanos Forsskal) juveniles

Groups of milkfish juveniles (mean initial weight 7.7 g) were fed semipurified diets containing 0.9, 1.4, 2.1, 3.1, 4.1 and 6.1 g tryptophan/kg dry diet for 12 weeks. The mean crude protein content of the diets (containing white fishmeal, gelatin and free amino acid mixture to simulate the pattern of hydrolysed milkfish protein) was 49%. On the basis of the growth response, the tryptophan requirement of milkfish juveniles was estimated to be 3.1 g/kg diet. Fish fed low levels of tryptophan exhibited low weight gains and poor feed conversion ratios. Survival (92–100%) was consistently high in all treatments. Fish fed diets containing tryptophan levels greater than 3.1 g/kg had slightly lower survival rates. The activity of hepatic tryptophan pyrrolase showed no significant differences with increasing dietary tryptophan levels. No nutritional deficiency signs were observed other than the depression in growth rates in fish given the tryptophan deficient diets.     

Broodstock management and egg production of milkfish, Chanos chanos Forsskal

Abstract. The milkfish, Chanos chanos Forsskal, industry in the Philippines suffers from a limited supply of wild fry. The demand for milkfish fry has spurred research in artificial propagation to supplement the natural seed supply. Spontaneous maturation and spawning of milkfish beginning at 5 years of rearing in floating net cages or concrete tanks coupled with improved egg collection technique have increased daily egg collection to a maximum of 3 million eggs and provided adequate volumes of eggs for mass fry production. Annual egg collection and number of spawnings were markedly higher in cage-reared stocks older than 9 years old than stocks less than 9 years old. Egg collection of tank-reared stocks were comparable to those collected in cages. As feed constitutes a major portion of the operating expenses for establishing and maintaining milkfish broodstock, further studies must be geared towards defining optimum dietary requirements and ration size for gonadal maturation and spawning. Also environmental manipulation studies must be conducted for year-round spawning. Developments in these areas should ensure the production of maximum numbers of high quality eggs and fry year-round.     

The essential fatty acid requirement of milkfish (Chanos chanos Forsskal)

The essential fatty acid (EFA) requirement of milkfish was examined by a 12-week feeding trial using defined, purified diets at water temperature of 28–29°C and salinity of 32. The test diets contained varying levels of 18:0 (triglyceride form, TG), 18:3(n–3), 18:2(n–6) and (n–3) highly unsaturated fatty acids (n–3 HUFA). Milkfish juveniles were starved for 7 days and were than fed lipid-free diet for 30 days before the initiation of feeding trials. Low growth and feed efficiency together with high mortalities were observed in fish fed the lipid-free diet as well as in the EFA-deficient diet. Supplementation of 2% 18:2(n–6) to the tristearin based diet did not improve growth rate of milkfish as effectively as feeding with (n–3) fatty acids. The highest weight gain was obtained in milkfish fed a combination of 5% 18:0 + 1.0% 18:3(n–3) + 0.5% 20:5(n–3) + 0.5% 22:6(n–3) although the supplementation of 2% 18:3(n–3) alone or combination of 0.5% 20:5(n–3) + 0.5% 22:6(n–3) to the tristearin based diets were also effective for improvement of growth. Thus, (n–3) fatty acids, such as 18:3(n–3) and (n–3)HUFA were nutritionally more important than 18:2(n–6) for milkfish. The fatty acid composition of the polar lipids from whole body of milkfish juveniles fed the various test diets were influenced by the composition of the dietary fatty acids.     

Acute nitrite toxicity and methemoglobinemia in juvenile milkfish (Chanos chanos Forsskal)

Nitrite was about 55 times more toxic to milkfish juveniles in fresh water than in 16% brackish water: the 48-h median lethal concentrations were 12 mg NO₂N/l (95% confidence limit=7.4–19.6) and 675 mg NO₂N/l (95% confidence limit = 435.8–1,045.4) respectively. Methemoglobin levels were higher for a given concentration of nitrite in milkfish kept in fresh water than in the brackish water. Methemoglobin decreased to a normal level within 24–26 hours of the removal of nitrite.     

Hormonal changes accompanying sexual maturation in captive milkfish (Chanos chanos Forsskal)

Steroid hormone profiles accompanying sexual maturation in captive milkfish are described. There were no significant differences in levels of serum estradiol 17- (E₂) and testosterone (T) between immature male and female fish. Mean E₂ levels rose from 0.54±0.11 ng/ml in immature females (Stage 1) to 4.53±1.16 ng/ml in vitellogenic females (Stage 5), while T levels increased from 2.06±0.28 ng/ml to 38.4±9.26 ng/ml. E₂ and T levels were positively correlated to GSI and oocyte diameter. In males, serum T levels increased from 2.5±0.40 ng/ml in immature males to 27.73±5.02 ng/ml in spermiating males. A significantly higher T level was found in males with thick and scantly milt (spermiation index, SPI, 2) compared to males with scanty milt (SPI, 1) or males with copious, fluid milt (SPI, 3).Serum levels of E₂ and T, and the GSI in females rose significantly during the breeding season (April–June 1983). The levels of both steroids dropped below 1 ng/ml in spent females sampled in succeeding months. In immature males, T levels ranged from 1.11 ng/ml to 2.78 ng/ml and rose significantly to 21.52±8.38 ng/ml during the breeding season when GSI peaked. Serum T levels dropped to around 10 ng/ml in the succeeding months when only spent or regressed males were sampled.