摘要:

This paper is the first of a series reporting the results of a study on haematology ofTilapia zilli(Gervais) in Egyptian waters. Erythrocyte count, total and differential leucocyte counts and their seasonal variations were studied. A complete description of the different types of leucocytes in the blood ofT. zilliis given in detail.T. zilliis found to have medium sized red blood cells compared to other fishes. The analyses showed that it is one of the species having the highest leucocyte count. Polymorpho‐nuclear leucocytes are not recorded in the blood smears of this fis

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04516.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Some observations on the biology ofMastacembelus armatus(Lacepède) from Muzaffarnagar (U.P., India) have been made during the period July 1966 to June 1969. At a particular stage of maturity of the fish there is a close relationship between the gonad weight and the body weight which helps in determining the breeding period of the fish. Both male and female fishes mature simultaneously. The gonad weight influences the relative condition, while the visceral weight does not exert any significant effect on it. The development of the female gonads greatly affect the curve of relative condition, more than the development of male gonads, though the curve for male fish also shows a steady rise and fall in the seasonal variations of the relative condition. Seasonal fluctuations in relative condition correspond to its spawning season. InM. armatus, the presence of two peaks in the curve confirm two breeding seasons. The present studies have also elucidated to a certain extent the important aspect of the maturation and spawning habits ofM. armatusin North India. The fish has two breeding seasons of short duration during June and July and again in November. The mature ovaries of each season contain slight maturing ova of next season along with mature ova of the present season. The entire stock of ova measuring 0.16 mm and above are shed during spawning

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04517.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Clarias gariepinus(Burchell) can be stimulated to spawn in aquaria by hormonal treatment and the breeding habits could be observed. After pre‐spawning activities such as the raising of dorsal fins and chasing of the female, the male folds around the head of the female and small batches of eggs are laid, followed by some gas bubbles. Eggs are distributed by the female over a wide area. This behaviour agrees with field observations. The final stimulant to spawning under natural conditions is thought to be a substance called petrichor dissolved in flood waters that have run over dry groun

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04518.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The development of chromatophores and the formation of colour patterns inTilapia mossambicaare described. A number of colour patterns are associated with certain aspects of behaviour. Four different melanophore systems are involved in the colour pattern formation. There appear to be 14 patterns which, in various combinations, produce a series of colour patterns. Each of these may convey a different message to different species ofTilapia.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04519.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04520.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

A system for horizontal, discontinuous electrophoresis in thin sheets of polyacrylamide gel was developed to permit rapid and direct comparison of multiple samples of fish plasmas for population studies. The resulting electropherograms are suitable either for screening for enzyme polymorphisms or for densitometric scanning after gels are stained for total proteins. Each gel sheet (110×90×0.8 mm) can be used for simultaneous separation of 10–15 different samples. Since total voltage and the running time required for successful resolution of fine protein bands are greatly reduced in this system, minimal heating occurs within the gel matrix during electrophoresis. Up to 120 different blood samples (8 gel sheets) can be processed in about 8 h. Gel sheets are routinely stained overnight in Coomassie Brilliant Blue (0.1%, v/v), rinsed several times and stored overnight in 7% acetic acid to complete destaining. Particular gel sectors are then transferred to distilled water and mounted on glass microslides for photography or for densitometric evaluation with a Leitz microspectrophotometer. These procedures have been used to identify characteristic differences in the electrophoretic mobilities of plasma enzymes and albumin fractions from several populations of poeciliid fishes. Observed differences in albumin mobilities (albumin phenotypes) were verified by mixing isoaliquots of test plasmas with plasma samples containing albumins of known mobility. Resultant patterns for albumin bands for such mixed plasmas were indistinguishable from those obtained with plasma samples from the F1hybrid progeny of parents possessing albumins of characteristically different electrophoretic mobilities. Procedural details for gel casting, electrophoresis and sample evaluation are descri

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04521.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The construction and operation of a pressure tank suitable for experimental work on teleosts is described. The tank can be used to simulate depths down to 60 m. The design permits water to flow through the tank at all pressures in order to provide oxygen and remove metabolites but there is no increase in dissolved gases with increased pressure.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04522.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Eustrongylidessp. larvae were found to be numerous inBagrus docmac, Clarias mossambicusandHaplochromisspp. from Lake Victoria, rare inHaplochromisspp. and absent fromB. docmacandC. lazerafrom Lake George, East Africa. Larvae encyst in the mesenteries, spleen and inHaplochromisspp. also in the gonads. Unencysted larvae were observed in muscles. Cyst walls consisted of fibroblasts, collagen strands, and were often infiltrated with fat cells. Fatty changes were observed in infected spleens; the muscle tissue, around the unencysted worms, was digested and infiltrated with fibroblasts. Infected gonads, particularly ovaries were deformed and in heavy infections degenerated completely. The biological implication of this infection with larvalEustrongylidessp. on the host populations in Lake Victoria is discussed.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04523.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The first occurrenceof Lernaea cyprinacea(L.) in Scotland is given together with a summary ofLernaearecords for Britain including one other unpublished record. Source of the infection is discussed and host fish involved listed. General characters of the Scottish specimens are compared with those of Demaree, Fryer, Hu and Wilson.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04524.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Arctic char,Salvelinus alpinus(L.), captured during the summer, 1972, in Cumberland Sound, Baffin Island, fed mainly on planktonic amphipods (Parathemisto libellula, Pseudalibrotus glacialis), copepods (Calanus hyperboreus), and fish (Boreogadus saida, Myoxocephalussp.), but failed to utilize coelenterates, planktonic gastropods, and epi‐ and infauna. The considerable variation in the species composition of the diet of char of different lengths was due primarily to size selection. The average length of all individuals in stomach contents and of representatives of most food species increased with the length of fish. The minimum and maximum length of frequently ingested organisms increased four and 90 times, respectively, as char increased from 4 to 85 cm. Char less than 10 cm in length captured in rivers tributary to the Sound fed mainly on larval Chironomidae (Eukiefferiella bavaria) during the summer, whereas those longer than 10 cm fed predominantly on other char. During the winter the stomachs of the smaller individuals were always empty while the diet of the large char was restricted to other fish. Most species available to the char were consumed in proportion to their relative abundance in the rivers. The dry weight of stomach contents, when expressed on a unit weight basis, decreased with the wet weight of char in both fresh and salt water. Thus, fish 10 g in weight contained approximately 1.5 times more food in their stomachs than those weighing 1000 g. The stomach contents of char captured in salt water weighed approximately 11 times more than those of char of comparable size captured simultaneously in fresh water. The fish fed at random intervals during the day and ceased feeding at night. Arctic char, at all sampling areas, had reached a length of approximately 9.6 cm after four years. Upon migrating to salt water, their growth rate increased sharply with the result that after eight years they were 26.5 cm in length, reflecting food availability. The growth rate gradually decreased in fish older than nine years so that 20 year olds were approximately 70.0 cm in lengt

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1974.tb04525.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY