The Copepod/Artemia Trade-Off in the Culture of Long Snouted Seahorse Hippocampus guttulatus

This study investigated the effects of copepods and copepod conditioning strategies on the growth and survivorship of long-snouted seahorse (Hippocampus guttulatus) juveniles from 1 to 60 days post-parturition (DPP). Four dietary treatments were tested: 24h Isochrysis galbana enriched Artemia (control), freshly collected copepods, 48h unfed copepods, and 24h I. galbana enriched copepods. Juveniles fed any copepod-based diet exhibited significantly higher growth (P < 0.05) and survival than those fed enriched Artemia. Mean standard length increased from 1.3 ± 0.1 cm at release to 5.9 ± 0.2, 7.5 ± 1.4, 7.1 ± 1.2, and 7.3 ± 1.1 cm at 60 DPP for the respective treatments. Wet weight rose from 0.002 ± 1 g to 0.44 ± 0.07, 0.81 ± 0.4, 0.68 ± 0.3, and 0.76 ± 0.4 mg, while final survival reached 20%, 60%, 33.3%, and 56%, respectively. Compared with Artemia, copepods markedly enhanced juvenile performance, supporting faster growth and promoting beneficial behavioral traits which contributed to improved survival. These results demonstrate that copepods as a superior live feed for early juvenile H. guttulatus, but copepod conditioning strategies directly influence their nutritional quality and, consequently, seahorse growth and survivorship. The use of copepods for the first 60 DPP is therefore not only feasible but strongly recommended.