摘要:

SummaryGrowth, daily ration, and gastric evacuation rates of milkfish (Chanos chanos) that fed on natural food and supplement diet were evaluated. Milkfish fingerlings (5.5g) were stocked at 1.5 fish/m2in ten 12 m2concrete tanks layered with 15‐cm thick earthen bottoms. All tanks were regularly fertilized (16–20–0 and chicken manure) to maintain natural food production; 4 of the tanks additionally received a supplemental diet containing 34.3% protein and 4290 kcal/kg gross energy. Estimates or daily ration (based on dry weight of stomach contents) were calculated using the Elliotand Person(1978) and Eggers1977) models. Gastric evacuation rate was lower in fish that fed on natural food (1.57) compared to fish fed a supplemental diet (1.79). Consequently, the lower rate resulted in lower food intake and slower fish growth. When fish were provided a high quality supplemental diet, daily rations for fingerlings (35 g) to marketable size (116 g) ranged approximately from 0.60 to 19.68 kcal/fish/day. The deviation in daily ration (kcal/fish/day) from the above estimates may indicate the insufficient quantity of dietary energy taken by fish from natural food alone, which could be provided by supplemental

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00527.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryGlass eels (Anguilla anguilla, L. 1758) caught during ascent at the mouth of the River Tiber were kept in aquaria with freshwater and full strength salinity (35 %) for four months.Morphological features of glass eels at capture and after four months of experimental rearin are described. The structure of the gut, an important osmoregulatory organ, observed in glass eels in seawater experimental rearing suggests that they undergo an irreversible process of adaptation to freshwater, despite the fact of survival in seawater.

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00528.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryA stable extraction technique was developed to quantify the lipofuscin content of fish brains. Samples of brains of the same age but different size rass carp showed that a large part of the variation in lipofuscin content was related to the weight of the fish.

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00529.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryExperiments were conducted to determine the optimum dose of luteinizing hormone‐releasing hormone analogue (LHRHa) and pimozide (PIM) injected simultaneously to yield a high ovulation rate and produce sufficient eggs in the Asian catfishClarias macrocephalus. In June 1990, injection of 0.05 or 0.10 μg LHRHa/g body weight (BW) + 1 μg PIM/g resulted in 100% ovulation, while only 80% of gravid catfish injected 0.025 μg LHRHa + 1 μg PIM/g ovulated. Most of the eggs stripped from 6 out of 8 control fish were not mature. Fertilization and hatching rates of LHRHa + PIM‐induced fish (75–90% and 39–51%, respectively) were higher than those of control fish (36–39% and 0–1% respectively). In August and September 1990, at gravid catfish ovulated after injection of 0.05–0.10 μg LHRHa + 1 μg PIM/g BW. However, only 20% of the fish given 0.025 μg LHRHa/g + 1 μg PIM/g BW in August ovulated. No eggs could be striped from any of the control fish in August and September 1990. Techniques developed in this study, showed a simple and effective way of spawning captive catfish,C. macrocephalus. A simultaneous intramuscular injection of 0.05 μg LHRHa + 1 μg PIM/g and stripping of eggs at 16–20 h post‐injection have been tested to yield high ovulation, ferti

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00530.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

ResumeLa caracterisation ultrastructurale des cellules immunitaires hépatiques de juvéniles de muges (Lizasp.) permet de distinguer des petits lymphocytes et des cellules appartenant à la lignée monocytaire (monocytes, macrophages, mélano‐macrophages). Ces cellules immunitaires présentent des caractéristiques morphologiues comparables à celles observées chez divers chondrichthyens et téléostéens. Les macrophages manifestent la plus forte capacité phagocytaire. Les centres mélano‐macrophages (CMM) sont essentiellement constirués de macrophages contenant des résidus d'origine hépatocytaire (corps résiduels à lipofuchsines). La structure et la taille des CMM reflètent l'activité non spécifique de phaocytose des macrophages en relation avec différents états physiologiques du Poisson. L'utilisation de ces critères, comme indicateurs de l'état sanitaire des muges juvéniles dans les milieux margino‐littoraux plus fortement con

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00531.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryAt a time when environmental pollution is a major issue the need for suitable monitoring systems has become paramount. There are in existence a number of methods for determining pollution levels in surface waters, however they often lack in specificity. Biological systems, therefore, are often deemed most suitable. Many organisms may be used as biosensors but studies incorporating fish have been most prevalent to monitor ventilatory response, activity levels, avoidance or rheotactic behaviour. More recently, work has concentrated on the use of the weakly electric fish,Gnathonemus, (family Mormyridae), which is characterised by the possession of electric organs near the tail. The fish use these electric organs to generate and transmit small electrical impulses, less than IV, into the surrounding water to communicate and navigate. Changes in the rate of pulsing can be used to identify the presence of certain chemicals in the water source.

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00532.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe accidental introduction and establishment of a population of the sanuivorous swimbladder nematode,Anguillicola crassus, in eels in an area of the Baltic Sea off the coast of Sweden that is affected by thermal water discharge was studied bi‐annually over a 5‐year period. In 1987, none of 387 eels examined was found to be affected. The first case of infection was recorded in 1988 and within 3 years the prevalence of infection had increased to about 60 %. By 1991, this was the most heavily infested area in Swedish waters. Whereas for yellow eels in the surrounding archipelago records have been kept only sporadicall since the infestation became established, in 1989–91 it was observed that both the prevalence and the abundance of infection were significantly higher in spring than during the second half of the year. When the frequency distributions of parasites for this period 1989–91 are compared, it is evident that this seasonality is connected with an autumn increase in the proportion of eels free from infestation, rather than a reduced proportion of those heavily infected. Furthermore, no seasonality was noted in the proportion of developmental stages of the parasite. Consequently, the observed seasonality is suggested mainly to be an effect of immigrating heat

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00533.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryTrichodina acuta, Lom1961;T. nigra, Lom1960;T.pediculus, Ehrenberg1838;T.perforata, Lom, Golemansky, Grupcheva1976;T.rostrata, Kulemina1968; andTrichodinella subtilis, Lom1959 from common carp as well asTrichodina domerguei domerguei(Wallengren1897; andT.tenuidens, Faure‐Fremiet1943 from sticklebacks are reported for the first time in eastern German

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1993.tb00534.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY