Effects of food availability on metabolism, behaviour, growth and their relationships in a triploid carp

Abstract

Metabolism, behaviour and growth are highly flexible in fish species, and inter-individual variation in these traits is evolutionarily and ecologically significant. It has long been suggested that these traits co-vary, although their relationships are debated. In the present study, we investigated whether metabolism, behaviour, growth and the potential relationships among them vary with food availability in sterile triploid carp. In this experimental animal model, we investigated the standard metabolic rate (SMR), growth performance and personality traits (i.e. activity, exploration and boldness) of juvenile individuals before and after 25 days of rearing in which fish were fed either once or twice a day to satiation. Inter-individual differences in SMR in each group showed high repeatability across the experimental period, and twice-fed fish showed higher SMRs than once-fed fish after 25 days of rearing. Compared with the once-fed group, the twice-fed group showed higher feeding rates (FRs) and lower feeding efficiencies (FEs) but similar specific growth rates (SGRs). None of the personality traits was affected by food availability. Furthermore, both boldness and exploration were highly repeatable throughout the experiment in the group fed twice a day, whereas only exploration showed repeatability in the group fed once a day. In the once-fed group, SMR and the personality traits were positively correlated with FR and negatively correlated with FE and/or SGR; however, these relationships did not exist in the twice-fed group due to the surplus of food. These results suggest that food availability significantly affects physiological, behavioural and ecological processes in these fish by altering the trade-off between metabolism and growth.

The effect of personality measurement conditions on spontaneous swimming behavior in the pale chub Zacco platypus (Cyprinidae)

“…The experimental setup was similar to those described in Tang & Fu (2019). Specifically, I used four rectangular tanks (length × width × height: 70 × 35 × 35 cm) as arenas to measure spontaneous swimming behavior in the different contexts, as in previous studies (Liu & Fu, 2017; Fig. 1).…”

“…To record movement in the exploration context, fish remaining in the shelter area were gently chased into the open area of the arena and acclimated for 10 min with the small door between the open and hidden areas closed. Then, a novel object (a black, round, plastic ball with a diameter of approximately 2 cm, Liu & Fu, 2017) was carefully placed on the arena bottom 40 cm from the small door ( Fig. 1), and the movements of the fish were recorded by the webcam for 10 min.…”

“…For example, a previous study in blue gourami (Trichogaster trichopterus) used a 40 × 60 × 40 cm arena (Bisazza, Lippolis & Vallortigara, 2001), and a 90 × 30 × 45 cm arena and 1.3-cm-diameter novel object were used for the guppy (Poecilia reticulata) (De Serrano, Fong & Rodd, 2016). A 50 × 20 × 36 cm aquarium and 1.8-cm-diameter novel object were used for zebrafish (Lucon-Xiccato & Dadda, 2014), and identical conditions were adopted in crucian carp (Liu & Fu, 2017). Thus, the fact that previous studies as well as the present study found a positive relationship between activity variables such as speed (or percent time moving) and exploration variables (distance and latency to explore the novel object) might have occurred because more active fish spend more time swimming at higher speeds and hence show a shorter distance to the object and exploration latency than do less active individuals (Liu & Fu, 2017;Tang & Fu, 2019).…”

“…The novel object test has been widely used in personality research to assess exploratory behavior (i.e., curiosity towards novelty) and neophobia (i.e., fear of novelty) (Galhardo, Vitorino & Oliveira, 2012). Exploration is usually evaluated in terms of the distance or latency associated with the inspection of a novel object (Liu & Fu, 2017). For activity measurements, fish biologists usually use the characteristics of spontaneous activities (movements without external stimulus) in an arena, for example, the median swimming speed and percent time moving during a given period (Brown & Irving, 2014;Liu & Fu, 2017).…”

“…Exploration is usually evaluated in terms of the distance or latency associated with the inspection of a novel object (Liu & Fu, 2017). For activity measurements, fish biologists usually use the characteristics of spontaneous activities (movements without external stimulus) in an arena, for example, the median swimming speed and percent time moving during a given period (Brown & Irving, 2014;Liu & Fu, 2017). It has long been recognized that many animals exhibit a so-called 'behavioral syndromes', as bold individuals are typically more exploratory and active than other individuals (Sih, Bell & Johnson, 2004;Sih et al, 2012;Martins & Bhat, 2014); i.e., personality traits are highly correlated, at least with regard to boldness, exploration and activity.…”