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M. Sc. Dissertations

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Subject: Fisheries × End date: 2009 × Start date: 2009 × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Studies on the breeding behaviour of guppy fish, poecilia reticulata (Peters), under laboratory conditions
    (CCSHAU, 2009) Godara, Sunita; Yadava, N. K.
    Guppy (Poecilia reticulata (Peters)) is an important ornamental aquarium fish. Courtship behaviour of this fish has been of interest to ecologists and evolutionary biologists. This is a cannibalistic fish which creates problems in keeping this fish in the aquaria. The adult guppy fishes were procured from the local market. These fishes were put in an aquarium of 24” ×12”×12” size, having filled with pond water. The fishes were fed on natural food @ 800-1000 zooplankton per aquarium on alternate days and artificial food (Toya Fish Food) @ 1g per aquarium twice a day was given. These feed levels kept the hydrological factors at optimum range. The aquarium was provided with water plants like Hydrilla and Ceratophyllum to give shelter to the new born. The latter were segregated each day and then transferred to other culture tanks as explained above to avoid predation by the adult fishes. The length and weight of the growing male and female fishes fed on above mentioned feed was monitored at different ages. The age specific size of the fishes was then determined. Mature males and females in different ratios were taken in the experimental aquarium and their behavioural displays towards each other were recorded in large number of trials and comparisons were made. The observations on female and male mate choices as influenced by the size, color and number of opposite sex and reproductive stages were recorded. The time budget of males and females of different ages and reproductive stages, and in different sex ratios were also recorded. The effect of previous feeding levels on the future time budgets of males was also studied. In breeding experiments, effect of different sex ratios (female: male) on the fecundity of female guppy fish was recorded. Likewise, effect of four protection designs on the gestation period and fecundity of female, and survival of young guppy fish were determined. Guppy fish raised on the recommended food source showed proportionate body growth with age. The anal fin in 8 weeks old males (2.5 cm) developed in to gonopodium and in 12 weeks old males (3.0 cm) gonopodium hood was developed. At this age/size, the males were considered to be capable of mating, although it was not certain whether sperms were available or not in such males. Males showed sigmoid displays and sneaky mating attempts where as females showed approach and fleeing behavior. In 1: 1 female: male ratio, all the males showed sigmoid displays only, and none showed sneaky mating attempts. However, when the males of different ages/sizes competed for the mate, they showed both kinds of displays; the frequency of sneaky display/ attempt was lower than the sigmoid display. It was further indicated that males of 3.5 cm length were sexually mature to attract the virgin females for mating, and female of guppy fish preferred large males for mating over the smaller ones and orange males over the dull coloured males. The female of guppy fish were found to copy the mate choice behaviour of other female in competition. Like female guppy fish, the males also had distinct choice for females of large size and a reproductive stage. The males showed maximal preference for mature virgin and bearer-unmated females. When two males compete for a virgin or bearer-unmated female, the first male showed, in majority of the cases, sigmoid display whereas second male in majority cases resorted to sneaky mating attempts. The same trend was followed in case of females with other reproductive stages. Young males of guppy fish (up to 4 weeks old) spent most of their time in feeding, which was reduced gradually with the age (size) of the fish. When a virgin mature female was provided to a male, the young males engaged mostly in feeding whereas mature males engaged in the pursuit of females. When multiple females were provided to a male, the latter involved more and more in the chasing of females. The present feeding level of the males also influenced the future feeding and courtship behaviour of the males. Female fishes in all the reproductive stages, if kept alone, spent most of their time in feeding. Presence of males severely influenced the time budget of female guppy fishes. Variation in sex ratio was found to influence the fecundity in female guppy fish. An optimum 1: 3 sex-ratio resulted into maximum fecundity in the females of this fish. All the female showed almost equal gestation period before giving birth to the young ones (range 21-25 days). The fecundity, though could not reach at optimum level as realized in previous experiment, yet it was uniform (about 58) in all the four types of aquaria. The survival of young fry and young fishes in aquarium design-II was significantly higher than those in other three aquarium designs.