Journal of Fish Biology (2012) 80, 218–224 doi:10.1111/j.1095-8649.2011.03156.x, available online at wileyonlinelibrary.com Morphological, physiological and behavioural response patterns of carp gudgeon Hypseleotris spp. to food deprivation: implications for assessing health N. S. P. Ning*†‡, S. Hladyz*§, B. Gawne*‡, S. Maffei*‡, A. Price*‡ and D. L. Nielsen*§ *The Murray-Darling Freshwater Research Centre, P. O. Box 991, Wodonga, Victoria, 3689, Australia, ‡La Trobe University, P. O. Box 991, Wodonga, Victoria, 3689, Australia and §CSIRO Land and Water, P. O. Box 991, Wodonga, Victoria, 3689, Australia (Received 13 June 2011, Accepted 4 October 2011) Morphological (growth, Fulton’s condition factor), physiological (per cent dry mass, total lipid content) and behavioural (activity levels) response patterns of carp gudgeon Hypseleotris spp. were examined in response to food deprivation during a 56 day experiment. Considerable variability in the nature and magnitude of these response patterns was observed, suggesting that caution should be taken when interpreting changes in the health of small-bodied fishes based on individual response variables. © 2011 The Authors Journal of Fish Biology © 2011 The Fisheries Society of the British Isles Key words: condition indices; freshwater fish; prey availability. Fishes are commonly subjected to periods of food deprivation as a consequence of the spatial and temporal patchiness of food availability in aquatic environments (M´ endez & Wieser, 1993; Mehner & Wieser, 1994). Periods of food shortage can affect survival directly through starvation, as well as indirectly through effects on a range of morphological, physiological and behavioural attributes, including growth (Wieser et al., 1992), condition (Collins & Anderson, 1995) and foraging activity (M´ endez & Wieser, 1993; Sogard & Olla, 1996). For example, several studies have observed reduced growth rates and energy stores in food-deprived fishes and have argued that such fishes are more vulnerable to predation, disease and unfavourable environmental conditions and have less energy for foraging (Jonas & Wahl, 1998; Chick & Van Den Avyle, 2000). Despite the importance of food deprivation as a critical factor influencing fish health, most studies undertaken to date have focused on investigating the effects of food deprivation on a particular trait or group of similar traits corresponding to morphological or physiological condition (Wieser et al., 1992; M´ endez & Wieser, 1993). Morphometrics based on length and mass data and condition indices have †Author to whom correspondence should be addressed. Tel.: +61 2 60249650; email: nning@ hotmail.com.au 218 © 2011 The Authors Journal of Fish Biology © 2011 The Fisheries Society of the British Isles