Environmental Enrichment for Rainbow Trout Fingerlings: A Case Study Using Shelters in an Organic Trout Farm.

Physical enrichment can improve the welfare of captive fish. Previous research has shown that fish often show preference for enriched environments, which can also result in improvements in growth performance. However, effects of enrichment are not always positive and the design and extent of the enrichment needs to be carefully considered.

Proactive coping style in early emerging rainbow trout carries a metabolic cost with no apparent return.

The timing with which salmonid larvae emerge from their gravel nests is thought to be correlated with a particular suite of behavioural and physiological traits that correspond to the stress coping style of the individual. Among these traits, aggressiveness, dominance and resilience to stress, are potentially interesting to exploit in aquaculture production. In the present study a series of experiments were performed, with the purpose of characterising behavioural, metabolic and production related traits in rainbow trout juveniles from different emergence fractions.

Differences in stress and disease resilience related to emergence time for first feeding in farmed rainbow trout ().

Salmonid individuals show a relatively high variability in the time required to abandon the gravel nest where they hatch, the so-called 'emergence time'. Different behavioral and physiological traits have been shown to be associated with emergence time in wild salmonids. In general, early- and late-emerging fish have traits resembling those of proactive and reactive stress coping styles, respectively.

Interplay between daily rhythmic serum-mediated bacterial killing activity and immune defence factors in rainbow trout (Oncorhynchus mykiss).

Circadian rhythm is emerging as an important regulator of immune functions. However, there is a paucity of information on the influence of this biological phenomenon in the antimicrobial factors in teleost fish. This study investigated the dynamics and interplay of serum-mediated bacterial killing activity and immune defence factors throughout the light:dark (LD) cycle in rainbow trout (Oncorhynchus mykiss).

Emergence Time and Skin Melanin Spot Patterns Do Not Correlate with Growth Performance, Social Competitive Ability or Stress Response in Farmed Rainbow Trout.

In wild salmonid fish, specific individual behavioral traits have been correlated with the timing of fry emergence from their gravel spawning nests; Early emerging fish display more aggressive behavior and have a higher probability of becoming socially dominant, compared to fish that emerge at a later stage. Apart from aggression and dominance, other behavioral and metabolic traits, such as boldness, metabolic rate, or growth, have also been linked to emergence time. Altogether, the traits of early- and late-emerging fish resemble those of the proactive and reactive stress-coping style, respectively.