38 SEP TEMBER 2022 • WORLD AQUACULTURE • WWW.WA S .ORG densities than previously examined (26,500 fish/ ha; Burger et al. 2018) in freshwater ponds. Therefore, two studies were conducted to test whether Gulf killifish cohorts can be stocked throughout the warmer months and at greater densities. Research was undertaken at the South Farm Aquaculture Facility on the Mississippi State University campus in Starkville, Mississippi. In the first study, the effects of stocking time on growth rate and survival were evaluated. Two juvenile cohorts, 7-9 weeks old, were stocked one month apart and each cohort was evaluated over a 12-wk period. Each cohort was stocked into three ponds per cohort at 25,000 juvenile fish/ha, similar to Burger et al. 2018. Both cohorts grew rapidly, reaching 6.5 cm in length, and growth rate was not limited by initial size of fish stocked (3.5-3.9 mm total length). Both cohorts across all ponds reached market size in 22-32 days. The first cohort had lower survival than the second cohort (Table 1) but was comparable to a previous study (Burger et al. 2018). Variability in survival may have been related to a combination of water quality influences, including increased temperature, pH and ammonia and decreased alkalinity, as well as predation. In particular, variability in pH among ponds may have affected survival, as the pond with the highest pH had the lowest survival (12 percent). Although high pH issues are common in nursery ponds due to high productivity caused by fertilization, these conditions can be devastating to Killifish (Order: Cyprinodontiformes) have wide environmental tolerances, including salinity. The Gulf killifish Fundulus grandis is of particular interest as a live baitfish for marine sportfishing. For this reason, production protocols for Gulf killifish have been evaluated and modified since the late 1970s. Gulf killifish are desirable to recreational anglers and show economic potential if producers can meet demand by providing a constant supply at a market size of 6 cm or larger. However, they have not been widely adopted by producers, due in part to limited understanding of commercial-scale grow-out techniques to market size. The broad salinity tolerance of this species allows for unique rearing capabilities in low-salinity or freshwater environments such as inland ponds. The majority of past Gulf killifish growth studies in earthen ponds have been conducted in brackish water and resulted in an inconsistent culture period to reach market size (39-91 days) but relatively high survival (70-93 percent; Chesser and Allen 2020). More recent studies have shown that Gulf killifish can be acclimated to fresh water just seven weeks after hatching (Ramee et al. 2016) and grown out to market size in freshwater ponds (Burger et al. 2018). Following initial freshwater grow-out trials, it was apparent that further information was needed to guide potential inland killifish producers in making more informed decisions about stocking. To meet market demands, inland producers may need to stock ponds multiple times over a growing season at greater Addressing Knowledge Gaps for Freshwater Pond Culture of Gulf Killifish Brittany Chesser and Peter Allen FIGURE 1.Gulf killifish Fundulus grandis after a 12-wk study at Mississippi State University. Gulf killifish have not been widely adopted by producers, due in part to limited understanding of commercial-scale grow-out techniques to market size. The broad salinity tolerance of this species allows for unique rearing capabilities in low-salinity or freshwater environments such as inland ponds.
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