[Periods for growth and quality improvement of fish in context of animal welfare compliant management of commercial fish ponds--a literature review].

In Germany, management of commercial fish ponds requires consideration of animal welfare legislation. In particular, it is forbidden to immediately catch fish that have recently been stocked into put-and-take fishponds. Rather, after stocking is completed, a short-term fishing ban period needs to be adhered to that allows the fishes the opportunity to grow and/or significantly improve in overall quality. The duration of the fishing ban varies considerably among German federal states. A literature review, therefore, was undertaken to identify the amount of time required by adult fish to reach changes in various parameters of quality (proximate composition, fillet colour, odour/taste, stress response), and growth.The literature search revealed that some of the selected parameters (odour/taste, stress response) can change within 24 hours, potentially resulting in improved fish flesh quality. With a time span of about four weeks, feeding-induced changes in proximate composition took the longest among the parameters tested to realize significant changes in fish flesh quality. Transportation-related reductions in body mass are overcome and succeeded by net growth within one to two weeks depending on food availability. Maintaining the fish under species-specific conditions and providing the optimal environment to meet their physiological demands, however, are critical prerequisites for growth and quality improvement. In conclusion there is science-based justification for fishing ban periods ranging from 24 hours to four weeks. Final determination of its duration, therefore, remains a careful balancing of values.