Investigation on the changes in behaviour and feeding habit of fresh water fishes due to some parasitic and bacterial infestation with an emphasis on restoration of normal behaviour and nutritional quality

Abstract

Aquaculture is currently the fastest growing food-production sector in the world, newlinebut diseases remain a primary constraint to its continued expansion. As many pathogens newlinenaturally occur in aquatic environments, all forms of aquaculture are prone to disease newlineoutbreaks (Pillay, 2004), which are largely determined by host susceptibility (Falsted et newlineal., 1993). Parasitic organisms live at least of their lives in or on other organisms, the newlinehosts, and obtain their resources by utilizing host individuals. A vast number of potential newlinehost species and sites of infection (different organs) offers a wide variety of resources for newlineparasites. Parasite infections cause host behaviors to alter in ways that serve to mediate newlinethe detrimental effects of infection. Parasites utilise energy reserves of their hosts; this is newlinemost noticeable in species that undergo some visible growth or development within their newlinefish host. Fishes infected with strongly devastating parasites may exhibit markedly newlinereduced activity levels and therefore, have a lower energy requirement. Either way, the newlineeffects of parasite infection in fishes are frequently manifest as a change in energy newlineexpenditure and, subsequently, appetite and feeding behaviour. Many parasites, such as newlinetrematode metacercariae, have a predilection for sites such as the brain, eye or nervous newlinetissue, and such infections often impair sensory function (Holmes and Zohar, 1990). newlineHeavily infected fish therefore need to spend a greater proportion of time foraging to newlineattain a rate of food intake equivalent to uninfected conspecifics. Many fish parasites newlineaffect their hosts in ways that may impair competitive ability. The most obvious ways in newlinewhich foraging ability can be constrained are through reductions in prey detection, newlinereduced swimming speed and manoeuvrability (Crowden and Broom, 1980). Particular newlinecharacteristics of the foraging habitat may interact with infection status to determine the newlinerelative success of infected individuals in natural populations.