Interaction "nutrition-reproduction" in fish.

In wild fish, gonad maturation and spawning induce modifications in feeding behaviour and dynamics of body stores which are possibly responsible for metabolic disorders. Conversely, food manipulations can modify reproduction of captive female broodstock. A restricted diet during early stages of the life cycle delays the first maturation age, a quantitatively restricted food supply during the stages of oocyte differentiation reduces the egg number, while a reduction of food levels during the last phases of oogenesis has only a small effect on egg size, composition and hatchability.

Growth reduction in trout induced by naphthenic and isoprenoid hydrocarbons (Dodecylcyclohexane and pristane).

Rainbow trout were fed a diet containing 1% dodecylcyclohexane or pristane for 9 weeks. Feed intake was recorded daily and weight gain every 3 weeks. These animals were compared with fish receiving a hydrocarbon-free diet (groups fed ad libitum and pair-fed groups for which the ration provided was the amount of food consumed by the hydrocarbon-contaminated fish, the day before).

Utilization of dietary urea in rainbow trout.

Experiments were conducted to examine the potential utilization of dietary urea by rainbow trout. A control diet and two diets supplemented with 1 and 3% of urea were fed to fish. Postprandial levels of urea and ammonia in blood plasma, and postprandial excretion of these metabolites were followed during 24 h.