JOURNAL OF THE Vol. 42, No. 2 WORLD AQUACULTURE SOCIETY April, 2011 Advances in Breeding and Rearing Marine Ornamentals Ike Olivotto1 Department of Marine Sciences, Universit`a Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy Miquel Planas ◦ Instituto de Investigaciones Marinas (CSIC), Eduardo Cabello n 6, 36208 Vigo, Galicia, Spain Nuno Simoes˜ Unidad Multidisciplinaria de Docencia e Investigaci´on – Sisal, Facultad de Ciencias, Universidad Nacional Autonoma de M´exico (UMDI-Sisal, FC, UNAM), M´exico G. Joan Holt Department of Marine Science, The University of Texas at Austin, Marine Science Institute, Port Aransas, Texas 78373, USA Matteo Alessandro Avella Department of Marine Sciences, Universit`a Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy Ricardo Calado Centro de Estudos do Ambiente e do Mar (CESAM)/Departamento de Biologia da Universidade de Aveiro, Campus Universit´ario de Santiago, 3810-193 Aveiro, Portugal Abstract This work addresses the most relevant advances in the breeding and rearing of marine ornamental species. The main breakthroughs in marine ornamental fish culture are discussed, with seahorses deserving a section of their own as a result of their conservation status and unique biology. Details on spawning, embryo development, larval rearing, plankton culturing, and tank design are presented. In addition, with the increase in popularity of ornamental invertebrates in reef aquariums, details on the culturing techniques of some of the most traded invertebrate groups (e.g., live rocks, corals, anemones, polychaetes, mollusks, decapod crustaceans and echinoderms) are also discussed. Finally, the last part of this work highlights the concerns toward the establishment of sustainable collection, production, and trading practices for marine ornamentals as well as the urgent need to develop reliable traceability protocols to distinguish sustainably caught and/or cultured specimens from wild ones. This work represents not only an exhaustive and updated bibliographical source but also a starting point for all those who want to contribute to the development of this fascinating research field. Although coral reefs cover less than 1% Earth. They support over 4000 fish species, of the marine environment, they are unani- about 800 species of reef-building corals and mously considered among the most biologi- several thousands of other reef invertebrates cally rich and productive ecosystems on the (cnidarians, sponges, mollusks, crustaceans, and echinoderms; Paulay 1997). The past few 1 Corresponding author. decades have been characterized by negative © Copyright by the World Aquaculture Society 2011 135 136 OLIVOTTO ET AL. anthropogenic effects on coral reef ecosystems, reefs (Tlusty 2002; Pomeroy et al. 2006). This such as sedimentation, nutrient enrichment due approach may not only generate an alternate to human waste and agriculture run-off, over- supply of marine ornamental specimens but will fishing, and global climate change (Baskett also allow researchers to collect valuable infor- et al. 2010; Selig and Bruno 2010). The inten- mation about their life history (age at maturity, sive fishing effort required to supply the marine fecundity, etc.) to improve the management of aquarium trade may also have played an natural stocks and our understanding of how important role in the decline of coral reefs. these organisms respond to human impacts. Unlike freshwater ornamental species, where This work addresses the most relevant over 90% of fish species are currently pro- advances in the breeding and rearing of marine duced in captivity, the vast majority of marine ornamental species. The main breakthroughs in aquaria are stocked from wild-caught speci- marine ornamental fish culture are discussed, mens (Wabnitz et al. 2003). In addition, less with seahorses deserving a section of their conscientious traders continue to support the own as a result of their conservation sta- use of destructive fishing techniques, namely tus and unique biology. Advances concerning the use of cyanide, to anesthetize highly priced the culture of marine ornamental invertebrates fish species. The use of this poison is known (i.e., live rock production, coral propaga- to harm targeted, as well as non-targeted, tion, anemones, polychaetes, mollusks, decapod reef fishes and its deleterious effects on sev- crustaceans, and echinoderms) are also pre- eral marine invertebrates are also documented sented and discussed. The last part of this work (Barber and Pratt 1998; Hanawa et al. 1998; highlights the need to establish sustainable col- Mak et al. 2005). The promotion of bleaching lection, production, and trading practices for in reef-building corals after exposure to cyanide marine ornamental species as well as to develop is certainly one of the most dramatic effects reliable traceability protocols to distinguish sus- of the use of this poison to collect live reef tainably caught and/or culture specimens. fishes (Jones et al. 1999; Cervino et al. 2003). Nonetheless, it is relevant to highlight that Marine Ornamental Fishes (Except cyanide poisoning is also used to supply the live Seahorses) food fish trade in Southeast Asia (Barber et al. 1997; Pomeroy et al. 2008) and that dynamite In recent years, there has been an increased fishing is only used to collect reef fishes for focus on supplying aquarium fishes through human consumption (Pet-Soede et al. 1999). closed system culturing. The development of It is estimated that from oceans to aquaria, reliable and sustainable hatchery procedures up to 80% of the traded animals die during for the captive breeding of reef fishes is now capture, shipment, handling due to the use of becoming essential to reduce pressure on wild poisons during collection, poor handling prac- populations and also because rearing fish in tices, and diseases (Sadovy and Vincent 2002; closed systems is likely to lead to the produc- Wabnitz et al. 2003). The poor survival of col- tion of hardier specimens that are far better in lected specimens through the chain of custody, captivity and survive longer (Wittenrich 2007). along with the current dependence of the marine It is hoped that much of the market demand aquarium industry on the collection of wild for the more popular ornamentals may even- specimens to supply an ever growing demand, tually be satisfied by cultured fish; however, urges researchers to find solutions to make in reality, most marine ornamental aquaculture the trade of marine ornamental species a more remains problematic. In fact, there are numer- sustainable practice. Aquaculture is commonly ous critical processes in early life history where considered a potential alternative, as the cap- deficiencies could represent a limiting factor tive production of some of the most heavily in captive rearing. Some of the main criti- collected species would certainly contribute to cal steps are spawning (which includes sexing relieving the current fishing pressure on coral the fish and the development of a reproductive ADVANCES IN BREEDING AND REARING MARINE ORNAMENTALS 137 competence), embryo development (which is are much more aggressive, whereas females strictly related to broodstock nutrition, mainte- present a rounder vent. nance, and genetics), hatching (which depends Some fish are able to perform sex rever- on the reproductive strategy), and the transition sal (hermaphrodites). There are simultaneous from endogenous to an exogenous feeding by hermaphrodites, where one individual possesses the larvae. both female and male reproductive tissue and It is well established that the life cycle of can act as either sex during a single spawning most coral reef fishes can be subdivided into event. Physical adaptation usually prevents self- three distinct biological/ecological phases: lar- fertilization. They represent a minority among vae, juvenile, and adult. To cultivate marine ani- aquarium fishes (e.g., Serranidae). Sequential mals, we must work on all life stages from eggs hermaphrodites are dominant and involve an to larvae, juveniles, and adults (Holt 2003). In individual acting as one sex during the early general, the hypothesis of many scientists is part of its life and eventually, if conditions that marine ornamental fish can be spawned and are appropriate, changing sex. They can be raised in captivity and second, the culture tech- subdivided in protogynous (sex change in the niques developed in the research laboratories female–male direction) and protrandrous (sex can be transferred to commercial production change in the male–female direction). Typical (Holt 2003; Olivotto et al. 2008a). examples of protrandrous species are clown- To start, breeding and cultivating marine fishes where the social status determines the sex ornamental broodstock has to be carefully cho- of the fish. The female is the largest, the male sen because high-quality breeders are essential is the second largest, and the nonbreeders are for successful larval rearing. When possible, progressively smaller as the hierarchy descends. captive-bred specimens should be preferred Typical protogynous species are dottybacks and over wild ones because they are hardier, far angelfishes. After determining the sex of the better in captivity, and survive longer, as they fish, the hypothalamus, pituitary gonadal axis are young fish (6–12 mo), and do not undergo should be activated. Environmental conditions, shipment stress. including photoperiod, temperature, and food As reproductive strategies used by fish are availability may be very important for this