Groups of 0+ Atlantic salmon (Salmo salar) smolts were transferred to duplicate seawater tanks, and subjected to five different ration levels, 0% (starved), 25%, 50%, 75% or 100% (full fed). Waste feed was collected after each meal. After six weeks all groups were re-fed in excess. During the trial period body weight and length increased significantly in the 50, 75 and 100% groups, while no significant changes in body weight were observed in the 0% and 25% groups. A significant decrease in SGR was observed in the 0 and 25% groups during the first month in sea water. After re-feeding, SGR increased in all groups. All groups, except the previously starved group, showed peak SGR between weeks 6-8 and 8-12. Food restriction at 0% and 25% of full ration for a period of six weeks resulted in significant osmotic disturbances. After six weeks in sea water, plasma Cl⁻ levels were higher in the 0% group than in the other groups. Branchial Na⁺,K⁺-ATPase activity increased in all groups following exposure to seawater. Re-feeding caused a transient increase in branchial Na⁺,K⁺-ATPase activity after two weeks in the previously starved group, with a concurrent reduction in plasma Cl⁻ levels. Previous exposure to different ration levels significantly influenced growth rate and mean body size. Compensatory growth and partial size compensation was seen in the 0, 25 and 50% feed deprivation groups, whereas full size compensation was found in the 75% group.

The effects of two benthivorous fishes, common carp (Cyprinus carpio) and calbasu (Labeo calbasu), on bottom soil resuspension, water quality, nutrient accumulations, fish diet and growth of rohu (Labeo rohita) were compared. In this study, individual tanks receiving bottom soil and water from a central pond were used to more naturally simulate rohu polyculture pond conditions. Two treatment combinations were performed in triplicate for 4 weeks: 6 rohu plus 3 common carp per tank and 6 rohu plus 3 calbasu per tank. Resuspension of bottom soil, free CO₂, and nitrogen and phosphorous concentrations in the water column were greater in the tanks with common carp while dissolved oxygen, pH, and total alkalinity were lower. Common carp increased the % nitrogen and % phosphorous accumulation in plankton and fish, while these nutrients were reduced in benthic macroinvertebrates and bottom soil. Gut contents of harvested calbasu contained a combination of benthic macroinvertebrates and zooplankton, rohu contained phytoplankton and zooplankton, and common carp contained almost entirely (82%) macroinvertebrates. Rohu shifted from zooplankton to phytoplankton when competition for zooplankton was higher in calbasu tanks. Since common carp preferred benthic macroinvertebrates they overlapped little with rohu for food. Common carp increased the harvesting weight and growth rate of rohu and thus had greater potential than calbasu to increase yields for rohu polyculture farmers.