. S, a dominant, lethal, atitosomal gene, was discovered in Auburn University's population of Surotherodon aureus (=Tilapia auera). When present in the heterozygous state (S+). the S gene produces the saddleback phenotype. Saddlebacks are missing part of or all of the dorsal fin. Some fish thai are missing most of or the entire dorsal fin have additional fin disorders and are missing various combinations of the pectoral, pelvic, and anal fins. Each fin disorder is associated with gross skeletal anomalies. Viability in saddlebacks is reduced by 67% during the first three months of life. Those that survive are less resistant to stress and subsequent infection than normal fish. When challenged by Saprolcegnia sp., saddlebacks were far more susceptible to infection (P<0.01). When present in the homozygous state (SS), the gene causes death in fry prior to swim‐up. Thus, a single S gene reduces viability by 67%, and two S genes reduce viability by 100%. The S gene did not affect early growth or dressing percentage. Because it is a dominant gene, the S gene can be eliminated from any population in one generation by culling all saddlebacks.

The endangered Rio Grande silvery minnow (Hybognathus amarus) was induced to spawn in both 2012 and 2013, using hydrological manipulation of a conservation aquaculture facility to create floodplain habitat. Fish responded to the flood by leaving the stream and entered both deep (20–97 cm) and shallow (14–18 cm) low‐velocity off‐channel habitats, spawning in the deep ones; fish did not spawn in the stream. When water level was brought down from flood stage, fry actively moved into the stream 2.5 weeks postspawn. This study supports the hypothesis that this species is a floodplain spawner. The results show that habitat restoration of the Rio Grande to create floodplains is needed for recovery of this species as floodplains are both spawning and nursery habitats. The study provides guidelines about how deep floodplain inundation must inundate for spawning to occur and for the duration of inundation so fry can actively swim with the water when flood waters recede. This project also shows that a conservation facility can be used for all stages of fish's life history. Equally important, it shows that a conservation aquaculture facility can be used to conduct hydrological experiments to determine how an endangered fish will respond to changes in river management.

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The naturalized conservation aquaculture unit (refugium) at Los Lunas Silvery Minnow Refugium is the first purpose‐built, large‐scale conservation aquaculture mesocosm. The refugium is 0.2 ha in area, with 0.11 ha of interconnected water habitats, including a stream with sand bars, five ponds, shelves, marshes, attached bars, and overbank areas that can be inundated to create floodplains. The key components of conservation aquaculture management in the refugium are as follows: (1) no artificial feed is used, so that the fish develop the foraging strategies that will be needed in the wild and do not develop maladaptive behaviors associated with feeding; (2) the production of natural food organisms is based on indirect fertilization; (3) fish are subjected to managed predation, so that when stocked they are not behaviorally naïve; and (4) low stocking rates are used to mimic population densities in the wild. Results from 6 years of management and the lessons learned about facility design and conservation aquaculture management are discussed.