Knowledge on seahorses is generally scarce but has been increasing in recent years due to their conservation status. Seahorse culture is a quite recent activity in the field of marine aquaculture in most countries attempting it, and captive breeding techniques are available only for some species. With the aim of contributing to the development of breeding in captivity for conservative purposes, broodstocks of the European long-snouted seahorse (Hippocampus guttulatus) were established with 32 wild seahorses captured in Galicia (NW Spain). This study describes the methodologies applied to the maintenance of the broodstocks, with special reference to aquaria design, feeding, growth and breeding. Procedures of seahorse identification (morphologically and genetically) as a tool for broodstock management are also considered. The results achieved during the first year demonstrate a rapid adaptation of wild seahorses to captive conditions. Seahorses were fed exclusively on enriched adult Artemia and displayed high growth rates. However, fatty acid analyses performed on unfertilised eggs of captive broodstock showed a progressive decrease with time in the content of essential fatty acids (DHA, EPA), suggesting the need for improvement in the nutritional quality of broodstock feed. during the first year demonstrate a rapid adaptation of wild seahorses to captive conditions. 30Seahorses were fed exclusively on enriched adult Artemia and displayed high growth rates. 31However, fatty acid analyses performed on unfertilised eggs of captive broodstock showed a 32 progressive decrease in the content of essential fatty acids (DHA, EPA) with time in captivity, 33suggesting the need for improvement in the nutritional quality of broodstock feed. 3435 36

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The use of adult Artemia is uncommon in aquaculture and limited to feeding adults of species not accepting inert diets. The aim of the present study was the development of a standardized technique for adult Artemia production in small volumes (25-100 L), and the assessment of ongrowing and enrichment diets for enhancement of n-3 highly unsaturated fatty acid (HUFA) content. We firstly assessed the effect of initial nauplii density (1, 2, and 3 nauplii mL −1 ) and food dose (x1, x2, and x3 quantities of mixed Tisochrysis lutea, Spirulina, and Prolon) for production of Artemia. Intermediate nauplii densities and food doses yielded the best overall results (44-46% survival; 5.6-5.9-mm length; 365-456 μg Artemia −1 ). Secondly, four diets (mixtures of Tisochrysis lutea, Phaeodactylum tricornutum, Spirulina sp., Prolon, and Red Pepper) were tested for ongrowing. Ten short-time enrichments (STEs; 30 h) and a long-time enrichment (LTE; 9 days) were also assayed for n-3 HUFA (Highly unsaturated fatty acids) enhancement. The improvement in n-3 HUFA was rather limited in STE. However, LTE on a mixture of P. tricornutum, Prolon, and Red Pepper (regardless of further STE) in ongrowing Artemia yielded the highest contents in total fatty acids and in 20:4n-6 20:5n-3, 22:5n-3, and 22:6n-3. The quality of LTE Artemia was based on an equilibrated dietary source of protein (Spirulina), 20:5n-3 (P. tricornutum), and 22:6n-3 (Red Pepper). STE Artemia had a quality similar or even higher than that of captured zooplankton, and its use in our laboratory for the feeding of seahorses significantly enhanced breeding and newborn quality.