Culture of the guppy, Poecilia reticulata, in Singapore

• A. A. Fernando and V. P. E. Phang
• Department of Zoology, National University of Singapore, Kent Ridge, 0511, Singapore
• Aquaculture. Volume 51, Issue 1 , 15 December 1985, Pages 49-63

Abstract

Singapore is known internationally as a breeding centre for the guppy, Poecilia reticulata. About 30 domesticated colour pattern and tail shape varieties are reared, mainly for export. The culture of these varieties at two rural and eight resettled farms is described. All farms are small family concerns. The resettled farms practice monoculture of guppies while the rural ones integrated farming. Guppies are reared in large, shallow, outdoor, cement tanks and nylon cage-nets suspended in ponds. Water in aquaria and ponds has salinities from 0.5 to 9.0‰, at neutral or alkaline pH of 7.0 to 8.3. The sizes and stocking densities of aquaria and nets vary within and between farms. In breeding tanks, a male to female sex ratio of 1:3, 1:4 or 1:10 is maintained. Newborn fry are collected daily and placed in nursery aquaria. After 3 weeks, these fry are sexed: young males are transferred to grow-out cement tanks, and females to grow-out cagenets. Each farm has at least two ponds, one for water storage and the others for cagenet culture. Strains are cultured separately to maintain pure lines. Farmers improve colour patterns, size and fin shapes of the strains by continued mass selection. Four- to 6-month-old guppies are selected as brookstock and the rest, which meet export quality, are held in stocking aquaria and sold when demand arises. Each farmer prepares his own formulated diet for the fish. Supplemental foods like live tubificiids, commercial dried fish flakes, or floating pellets may be given to adults, and water fleas to fry. The rural farms add pig manure to fertilize the tanks. To remain viable in the future, farmers need to increase productivity by mechanizing cleaning, draining, and filling tanks and ponds, feeding, and harvesting of the fish. This will cut down on labour and its increasing cost. Understanding the genetics of economically important characters will also help farmers produce higher quality and more exotic strains.

Packaging of the guppy, Poecilia reticulata, for air transport in a closed system

• L. H. Teo, T. W. Chen and B. H. Lee
• Department of Zoology, National University of Singapore, Kent Ridge 0511, Republic of Singapore
• Aquaculture. Volume 78, Issues 3-4 , June 1989, Pages 321-332

Abstract

The aim of this work was to investigate the application of clinoptilolite, tris buffer and 2-phenoxyethanol in controlling the aquatic environment of a closed system involving guppies in polyethylene bags containing water overlaid with oxygen. In the experiments, 20 guppies were placed in a sealed plastic bag containing 400 ml water maintained at 25°C for 24 h. Clinoptilolite significantly reduced the concentration of ammonia in the water. The best concentration appeared to be 20 g/l since it gave the second greatest reduction of ammonia and the lowest mortality rate of the guppies. Higher concentrations resulted in turbidity of the water and higher mortality. Tris buffer (pH 8) was effective in maintaining a higher and more stable pH; the lowest mortality rate was found in the group treated with 0.02 M tris buffer. 2-Phenoxyethanol at concentrations of 0.11 and 0.22 g/l was effective in maintaining a zero mortality rate of guppies. A combination of 2-phenoxyethanol (0.11 g/l) with clinoptilolite (20 g/l) or tris buffer (0.02 M) was effective in maintaining low mortality rates of guppies but a combination of clinoptilolite and tris buffer did not work (11.7% mortality). A combination of all three chemicals successfully maintained the mortality rates of guppies at low levels up to 48 h with 30 fish in each bag. However if the number of fish in each bag was increased to 40, the mortality rate was too high (17.5%) to be acceptable. Increasing the dosage of 2-phenoxyethanol to 0.22 g/l and increasing the water volume in each bag to 600 ml allowed us to increase the number of fish in each bag to 50 or even 60 and still maintain reasonably low mortality rates of 2-6% for up to 48 h, a time period more than adequate for the shipment of fish by air to any oversea destination. In all the above experiments neomycin sulphate at 20 mg/l was added to the water to prevent a bacterial build-up. The results of this work indicate that guppies can be transported at higher packing densities, for long periods of time, and can be received in good condition when the method developed here is applied as a packing practice.

Guidance of groups of guppies (Poecilia reticulata) to allow sorting by computer vision

• I. Karplus a, V. Alchanatisb and B. Zion b
• aDepartment of Aquaculture, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
• bInstitute of Agricultural Engineering, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel
• Received 30 March 2004; accepted 28 September 2004. Available online 10 December 2004.

Abstract

Prior to marketing, ornamental tropical fish are currently sorted, graded and counted manually; a process that is labor intensive, stressful to fish and inaccurate. Manipulation of fish movements at our will is a key element in the development of a device for automatically sorting, grading and counting fish by a computer vision system, and the present study is one step towards the development of such a fish-friendly sorting device. The positive phototactic and rheotactic innate responses of guppies (Poecilia reticulata) were exploited to induce them to swim through transparent pipes or narrow channels, to render them ready for inspection by a computer vision system. Water flow direction and velocity, water level, and illumination were effective in inducing fish to move from one container into the other via a narrow transparent pipe. It was attempted to separate guppies moving in groups into individually spaced fish, by introducing an obstacle into a narrow channel or narrowing the transparent pipe.

Strain differences in cultured fish - Isozymes and performance traits as indicators

• J. Macaranas a and Y. Fujio b
• a Marine Science Institute, University of the Philippines, Diliman, Quezon City, The Philippines
• b Department of Fishery Science, Faculty of Agriculture, Tohoku University, 1-1 Amamiyamachi, Tsutsumidori, Sendai-shi, Japan
• Aquaculture. Volume 85, Issues 1-4 , March 1990, Pages 69-82

Abstract

A comparison of genetic changes in broodstocks or strains of five cultured fish species, namely, Japanese char, Nile tilapia, Mossambica tilapia, Japanese common carp, and the guppy, showed them to be influenced by the intensity of selection pressure and/or by the history of culture. Allele distributions at polymorphic loci were mainly governed by genetic drift and also by introgressive hybridization or gene exchange. Such genetic changes are expected to occur also at loci controlling performance traits. Using the guppy, Poecilia reticulata, as a model fish, 10 different strains consciously selected for body colour patterns, body size, and finnage, and which were genetically differentiated into six race level groups, were investigated for strain differences in eight growth-related and reproductive traits. Strain differences were significant for all traits and phenotypic differences, expressed as [d]/m = 'P1 - P2||/(P1 + P2), were significant in at least one out of eight traits for every strain pair. Of the eight quantitative traits, survival at Day 60, fertility ratio, and brood size showed higher variation, as seen from their coefficients of variation and [d]/m range. The correlation of overall [d]/m between strains and their corresponding Nei's genetic distance was low (r = -0.104) but individual trait correlations with Nei's D were significant for survival at Day 0 and male body length at Day 60. Results suggest that strain differences are characterized by a random segregation of alleles both at biochemical and trait loci but that occasionally, linkage may occur. The utility of isozyme markers and the [d]/m index are discussed.

Sex control and manipulation in fish

• Fumio Yamazaki
• Laboratory of Embryology and Genetics, Faculty of Fisheries, Hokkaido University, Hakodate, Japan
• Aquaculture. Volume 33, Issues 1-4 , June 1983, Pages 329-354

Abstract

The basic nature of the greatly diversified sexualities in fish can be considered from the aspects of the control mechanisms, physiological and genetic sexes. The potencies of sex steroids to induce sex reversal are different for each steroid. Functional sex reversal from female to male is carried out by using 17-methyltestosterone, 19-norethynyltesto-sterone or methylandrosterone. 11-ketotestosterone or androsterone have also been used but the dosage required was higher than those of synthetic androgens. The effective range of methyltestosterone required to induce masculinization in medaka, goldfish and tilapia is 20-30 mg/kg diet and rather wide, in the range1-100 mg/kg diet, in zebrafish. In rainbow trout, the optimum concentration is quite low, in the range 0.1-3 mg/kg diet. In this species, treatment with more than 10 mg/kg diet induces sterile or hermaphroditic gonads and rarely induces sex reversal. Sex differentiation commences after hatching, either before or after the initiation of feeding. In viviparous fish such as guppy, the female is differentiated prior to parturition, and so the administration of methyltesto-sterone is started before parturition and continued until birth. In rainbow trout the first 8 weeks of the oral treatment are important. Treatment for longer than 60 days may be meaningless. Phenotypical feminization is induced successfully by using estradiol-17. Estrone, diethylstilbestrol or ethynylestradiol are also used. Treatment with steroids is usually carried out by feeding. In salmon, where male sex differentiation is initiated before feeding commences, other procedures are used, such as immersion of alevins. Chromosome manipulation also has great possibilities for sex control. Artificial gynogenesis in species having female homogamety produces all female fry. Triploidy produces sterile fish in rainbow trout. This can be achieved easily by applying hydrostatic pressure or temperature shock. Particularly fruitful techniques for control of sex in aquacultured fish will involve the combination of steroid treatment with chromosome manipulation.

Masculinization of Poecilia reticulata by dietary administration of synthetic or natural androgen to gravid females

• Soosamma Kavumpurath and T. J. Pandian School of Biological Sciences, Madurai Kamaraj University, Madurai, India
• Aquaculture. Volume 116, Issue 1 , 15 September 1993, Pages 83-89

Abstract

The masculinizing effects of three synthetic androgens, 19-nor-ethynyltestosterone (100-500 mg/kg food), 17-ethynyltestosterone (100-500 mg/kg food), 9(11)-dimethyltestosterone (100-400 mg/kg food) and a natural steroid, androstenedione (100-400 mg/kg food), were investigated in the guppy, Poecilia reticulata. Androgens were administered orally to gravid females for a period of 5-24 days, prior to parturition. All the resulting progeny were sampled to examine the sex ratio. Essentially all male populations were produced following treatment with androstenedione, 19-nor-ethynyltestosterone, and 17-ethynyltestosterone at doses of 200, 300 and 500 mg/kg food, respectively. 9(11)-Dimethyltestosterone was associated with incomplete sex reversal and, at the highest dose used (400 mg/kg diet), increased mortality. Sex reversal of genetic females was confirmed by subsequent progeny testing, 8 of 34 individuals generating all female populations when crossed with normal females. Androstenedione was the most potent androgen that ensured sex reversal with maximum survival and functional equality.

Production of a YY female guppy, Poecilia reticulata, by endocrine sex reversal and progeny testing

• Soosamma Kavumpuratha, and T. J. Pandianb a Department of Zoology, Fatima Mata National College, Kollam, Kerala, India b School of Biological Sciences, Madurai Kamaraj University, Madurai, Tamil Nadu, India
• Aquaculture. Volume 118, Issues 3-4 , 15 December 1993, Pages 183-189

Abstract

A YY-female Poecilia reticulata was produced by endocrine sex reversal followed by progeny testing. Heterogametic females (XY) produced by endocrine sex reversal were mated with normal males (XY) and subsequently treated with an estrogen-supplemented diet, 5-10 days prior to parturition. Progenies obtained from these fish were individually mated with sex-reversed males (XX) to identify their genotype. A single female was identified to have the YY-genotype, and produced only males when mated with a sex-reversed male (XX).

Absence of female conspecifics induces homosexual behaviour in male guppies

• Kristin L. Field*, and Thomas A. Waite*, †
• *Department of Evolution, Ecology, and Organismal Biology, U.S.A.
• †Department of Anthropology, The Ohio State University, U.S.A.
• Received 27 December 2002; revised 2 April 2003; accepted 3 December 2003. MS. number: A9511R. Available online 26 October 2004.

Abstract

Social environment can have dramatic effects on the expression of species-typical sexual behaviour. Using guppies, Poecilia reticulata, we asked how an all-male social environment affects male sexual behaviour. Males were assigned to either single-sex or mixed-sex groups. After 15 weeks, their sexual behaviour was assayed in the presence of three novel individuals of each sex. Males from single-sex groups performed higher rates of sexual displays and sneak copulation attempts towards stimulus males than did males from mixed-sex groups. Males from mixed-sex groups directed the majority of their sexual behaviour towards females using typical heterosexual behaviour. The social environment for each subject was then reversed for 2 weeks, after which subjects in both treatments showed a stronger tendency to display or sneak towards males. These findings reveal that homosexual behaviour is not readily extinguished when females become accessible and that it can be induced even after the ontogeny of heterosexual behaviour. While guppies may rarely occur in all-male groups in nature, these findings highlight the capacity for social environment to shape mating behaviour, which is particularly relevant for captive populations used in behavioural studies or conservation breeding programmes.

The effect of female presence on spermiation, and of male sexual activity on 'ready' sperm in the male guppy

• Chantelle C. Bozynskif1 and N. Robin Liley
• Department of Zoology, University of British Columbia
• Animal Behaviour. Volume 65, Issue 1 , January 2003, Pages 53-58

Abstract

This study examines the effect of female presence on the amount of 'strippable' sperm, and the relationship between male sexual activity and the amount of 'ready' sperm in the male guppy, Poecilia reticulata. The amount of strippable sperm was greater in males paired for one week with females than in isolated males. We separated these 'paired' males from females by a clear partition and thus exposed males to visual and possibly olfactory stimuli. In the second experiment, control males spent more time attending females and performed more sexual acts during a 15-min test period than males previously stripped of spermatophores. These results indicate that females play an important role in stimulating sperm availability in males and that the amount of ready sperm influences male sexual behaviour.

Spectral irradiance and foraging efficiency in the guppy, Poecilia reticulata

• Elizabeth M. White, Stuart C. Church, Laura J. Willoughby, Sarah J. Hudson and Julian C. Partridge
• School of Biological Sciences, University of Bristol, U.K.
• Received 19 January 2004; revised 20 February 2004; accepted 30 May 2004. MS. number: 7967. Available online 11 November 2004.

Abstract

The spectral composition of the light environment can have important implications for visually mediated behaviours. We examined how spectral irradiance influences the behaviour of guppies foraging for live zooplankton prey. Daphnia are semitransparent, transmitting human-visible wavelengths but absorbing strongly in the ultraviolet (UV). We first tested the hypothesis that UV wavelengths contribute to foraging efficiency. We then used lighting conditions that selectively blocked regions of the spectrum (UV, short-wavelength, medium-wavelength and long-wavelength light) to determine the effect of removal of these particular spectral regions on guppy foraging rate. Guppies foraged equally effectively under UV-present and UV-absent conditions, suggesting that UV wavelengths are not particularly important for detecting and locating prey under our experimental conditions. Similarly, foraging effectiveness was not significantly affected by the removal of short-wavelength information. In the absence of long wavelengths, however, foraging rate was significantly reduced. This suggests that long-wavelength information is particularly important in this foraging task. We used image analysis to measure the contrast of Daphnia against the background. Contrast was reduced in the absence of UV or long wavelengths but increased when short wavelengths were removed. Variation in contrast cannot, however, fully account for the results observed. It is also possible that the removal of long wavelengths hindered other factors such as motion perception.