View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by CMFRI Digital Repository Breeding and seed production of Clown fishes under captivity Breeding and seed production of Clown fishes under captivity Rema Madhu*, K. Madhu and T. Retheesh Central Marine Fisheries Research Institute, Post Box No. 1603, Ernakulam North P.O, Cochin, Kerala, India *E-mail: [email protected] 201 Introduction fishes or sea anemone fishes” are long ranked as one of the most popular attractions all over the Ornamental fish production for the aquarium world because of their tiny size, hardiness, attrac- industry is a multimillion dollar industry in the tive colour features, peaceful nature, high adapt- world. Aquarium keeping is amongst the most ability to live in captivity, acceptability to artificial popular of hobbies with millions of enthusiasts diet and their fascinating display behavior and worldwide. Although most fish kept in aquariums symbiotic relationship with the sea anemones. are from freshwater, the acquisition of marine or- Clownfishes are the most longstanding and in- namental fish has greatly increased in recent years tensively cultured family of marine ornamentals and is also popularized through children’s movies and are the best ranked in marine aquarium trade. by starring charismatic colourful fishes and other They were the first reef fish species bred success- creatures. Recent advances in fish husbandry and fully in captivity. However, large scale culturing aquarium gadgets and technology have further fa- of clownfish has not always been successful tech- cilitated the hobby. In India, marine ornamental nically due to the lower larval survival which usu- fish trade is an emerging area during the last two ally go through one or many larval stages, start out decades and the industry is further advancing. at a very small size, and are extremely sensitive Along with it ancillary business such as aquarium to external factors. The clown fish species most making, aquarium plants and live feed produc- studied is A. ocellaris. The technique used for this tion, grow- out culture etc. are also flourishing. fish has been used for a long time to establish the India has about 200 varieties of marine orna- protocol or guidelines for the breeding of other mentals, of which more than 50 have export po- clownfish such as A. chrysopterus, A. clarkii, A. tential. Among these, the clown fishes or anem- percula, A. melanopus and Premnas biaculeatus. onefishes belonging to the family Pomacentridae, From the Indian waters 15 species in the gen- comprising of genera Amphiprion and Permnas era Amphiprion and the single species of the have always been the most popular and sought genus Premnas have been reported (Madhu and after group. Altogether 28 species of clown fishes Madhu 2000). Most of the traded marine orna- were reported from the different geographical lo- mental fishes are being collected from the wild cations of the world. The members of the family and hence there is a great concern regarding the Pomacentridae commonly known as damselfishes depletion of the stocks due to over exploitation as and anemonefishes are a diverse group of marine well as the destruction of reef habitat and damag- fishes found in tropical seas, also have very high ing collection methods all over the world. Recent demand in marine ornamental fish trade. The fam- studies shown that captive bred clownfish are ily comprises 29 genera and 350 species inhab- generally hardier, disease free, and are better ad- iting in the coral reef ecosystems. Pomacentrids justed to life in aquaria than their wild-collected have been divided into four subfamilies: Amphi- specimens, and as a result the demand for the prioninae, Chrominae, Lepidozyginae and Poma- captive bred fishes are increasing. For the breed- centrinae. Under the genera Amphiprion, 29 ing of clown fishes under captive conditions, few species and a single species, the maroon clown important steps are to be followed. These include Premnas biaculeatus have been reported under selection of suitable broodstock, setting up the the genus Premnas. tank, broodstock feeding, maintenance of high Anemone fishes or clown fishes water quality, provision of suitable environmental parameters, creating suitable condition for spawn- The genera Amphiprion and Premnas belong- ing and system for raising the larvae and juveniles. ing to the family Pomacentridae and sub fam- ily Amphiprioninae commonly known as “clown Transportation of broodstock 203 CMFRI Manuel Customized training Book For the captive mass production of clown fish- of the pair dies. If the female dies first, the larg- es, the basic requirement is to have a sufficient est male rapidly changes sex into a female and number of broodstocks or breeding pairs which the second largest or dominant juvenile becomes can either be collected form the coral reef habitat an active male and that pairs up with the newly or can be purchased from the pet shop depending transformed female. By utilizing this adaptation, upon the availability. In the wild, the clown fishes pairs of clown fishes can be developed under cap- generally occupy in social groups centered in a tive condition by creating social systems. After a host sea anemone with a sexually active pair of period of 3 to 4 months of rearing for pair forma- adults and one to three juvenile or sub adult fish tion, in each tank one pair grew ahead of others and the female is larger than the male. The clown and becomes the spawning pair. As the newly fishes naturally exhibit monogamous pair forma- formed pairs will be very aggressive and spending tion and these pairs are to be collected for brood- time for fleeing the other subordinates rather than stock development and breeding programme. reproductive activity, it is very essential to stock In case such mated pairs are not available, fish each breeding pairs in separate tanks. of different size groups can be collected and al- lowed to form pair under captive conditions. In Tank set-up for broodstock order to make breeding pairs form the juveniles A clownfish broodstock/ spawning tank should groups, many social groups of clown fishes can be of 250 to 500 L capacity with a single healthy be collected from the wild and transported to the pair and host sea anemone. An ideal tank would laboratory. During transportation, the fish and the be a 3 ft x 2 ft x 2 ft with a layer of coral sand sea anemones should be kept in separate trans- at the bottom, few live rocks, bright lighting and portation containers. good filtration, preferably with an efficient protein skimmer to reduce the ammonia and organic ma- Pair formation terials in the system. A trickle filter could be used For pair formation, five fishes of each sex of with regular water changes to keep the nitrates different size groups need to be stocked together low enough for the anemone to do well. Since the along with a host anemone in a 500 L FRP tanks gonad development and spawning of clown fishes fitted with biological filter to reduce the aggres- are influenced by moon phases, the broodstock/ sion. Pair formation tanks have to be maintained spawning tanks should be kept at a place where in the hatchery with a light intensity of 2500 to the fish receive regular day/ night light cycle 3000 lux as the anemones require light for sur- (moon phase). Anemone is generally not required vival under laboratory conditions. The fish and to breed clownfish under captive condition. But anemones should be fed twice a day with wet generally the clown fish select a nest site adjacent feeds like shrimp, mussel and clam meat at the to the sea anemone for deposition of eggs. Moreo- rate of 15% of their body weight and live feeds ver an added benefit of having an anemone is that like Brachionus plicatilis, artemia nauplii and it may release compounds that help to protect the adult artemia. Environmental parameters such as eggs or even chemically induce immunity that temperature (26 to 29ºC), salinity (33 to 35 ppt), clownish have with the anemone. dissolved oxygen (4.6 to 6.2 ml/L) and pH (8.1 to 8.4) are to be maintained in all rearing tanks. Broodstock development and maintenance After the pairs are formed, they are transferred Sex change and pairing to glass aquaria for broodstock development. De- As the clown fishes are protandrous (male first) pending upon the production capacity and seed sequential hermaphrodites, a pecking order is es- demand, several pairs can be maintained in com- tablished in which the female is dominant, the mercial hatcheries. The broodstock are fed with male is subordinate to the female, and all the oth- meat of green mussel, shrimp, clam and fish egg, er juveniles are subordinate to the adult male and along with supplemental formulated feeds en- female. Thus generally all clown fish individuals riched with vitamins, minerals and algal powder start out as males and change into females when at the rate of 10% of their body weight and fed they reach larger sizes or under the situation of during day time at an interval of 3 h. Apart from loss of mate. The male and female form a mo- these, the broodstock are also fed with enriched nogamous pair bond that lasts until one member rotifer 800 to 1000 nos/ml and artemia nauplii 204 Breeding and seed production of Clown fishes under captivity (200-400 nos/ml) and adult artemia (3 to 5 nos/ of the water should be exchanged to avoid stress ml) every day. like a rapid increase in plasma corticol concentra- tion, depression of gonadal streroidogenesis, and Enrichment of rotifer and artemia subsequent development of gonadal atresia.