We compared growth of all‐female triploid (AFT; 87% triploid), all‐female diploid (AFD), and mixed‐sex diploid (MSD) rainbow trout Oncorhynchus mykiss in a 265‐d growth trial. Triploidy was induced by heat‐shocking eggs to prevent second polar body exclusion. Three AFT families, three corresponding full‐sibling AFD families, and three MSD families that were half‐siblings of the AFD and AFT families were used. Mean initial weights (SD) were 94 g (14), 84 g (12), and 112 g (14) for the MSDs, AFDs, and AFTs, respectively, and final weights (SD) were 521 g (22), 568 g (68), and 749 g (30). Growth was linear. Growth was highest for the AFTs (2.38g/d), lowest for the MSDs (1.58 g/d), and intermediate for the AFDs (1.78 g/d). No significant differences (P > 0.05) were found among treatments for survival, food conversion ratio, condition factor, liversomatic index, viceral fat, and dress‐out. By day 180, however, the majority of the MSD males were sexually mature, whereas the MSD females and the AFDs were still maturing; mean gonadosomatic indices at day 180 were 3.1 for MSD males, 1.1 for MSD females, 1.9 for AFDs, and 0.4 for AFTs. Monosex female trout, diploids and triploids, show promise for practical trout farming due to their faster growth and the elimination of males, which mature and lose flesh quality earlier. Farmers should consider AFT production, especially for markets using larger trout.

Artificial swim bladder deflation was examined as a technique to increase postrelease survival of largemouth bass Micropterus saltnoides caught from deep water. Depressurizalion was simulated with a hyperbaric chamber. Largemouth bass showed clinical depressurization signs when depressurized from a simulated depth of 3.5 m and were unable to immediately submerge when depressurized from 8.4 m. When depressurized from a simulated depth of 10.5 m. largemouth bass experienced 07c mortality when subsequently held at 14°C but 78% mortality when held at 28°C. Survivors floated for more than 6 h. a response that could expose them to higher water temperatures in stratified lakes and to increased predation. illegal harvest, and injury. Depressurized largemouth bass that had their swim bladders deflated by being punctured with a hypodermic needle were able to submerge and experienced no mortality when transferred to 14°C or 28°C. The punctured swim bladders were functional immediately. Growth over 4 weeks did not differ significantly (P > 0.05) between largemouth bass with or without artificially deflated swim bladders, and no deaths occurred over this period. We recommend artificial swim bladder deflation for largemouth bass showing depressurization signs and caught from depths greater than 6 m.