Coastal areas in Malaysia are often residential centres that have developed rapidly thus experiencing a sudden increase of urbanisation that contributes to increasing pollutants in the aquatic environment . In Malaysia, the increased pollutant input to aquatic environments is basically derived from anthropogenic activities; mainly agro-based and manufacturing industries, animal hus- bandry and sewage . The anthropogenic source of heavy metal pollutants such as Cd and Zn in coastal wa- ters were found elevated in adjacent to the industrial es- tates and urban  and ports . In conjunction with the increasing water pollution level in these areas, several studies have been conducted to indicate the coastal wa- ters pollution in cultured and wild organism. Several or- ganism such as green-lipped mussel, Perna viridis , blood cockle, Anadara granosa; shrimp, Penaeus mer- guiensis and catfish, Arius maculatus  have been used to as biomonitoring agent for heavy metals pollution in Malaysia. However, few studies have been done to indi- cate the trace metal content in the cultured or wild sea
Barramundi or Asian seabass, Latescalcarifer is one of the commercially important fish species widely cultured in several Asian countries. Nutrient requirements for this species has been well defined, considerable efforts have also been made in the three decades to develop nutritionally balanced and cost-effective diets (Glencross 2003). The commercial feed formulation for this species heavily depends upon the FM as the primary protein source. Although, a number of FM alternative ingredients of plant and animal origin have been investigated (Boonyaratpalin et al. 1998; Glencross 2003), use of locally available but nutritionally efficient feedstuff in barramundi feeds is warranted. Therefore, the present experiment was conducted to evaluate the replacement efficacy of protein from BSFL meal with FM protein in juvenile barramundi, reared in freshwater.
The culture of barramundi, or Asian seabass (Latescalcarifer), has occurred in Australia for more than 30 years. There has been sig- niﬁcant improvement in its culture especially for the juvenile and grow-out stages but bottlenecks still remain for the larval phase. These challenges include mortality at metamorphosis (about 19 dph), vaccuolation of the spine and brain, and high sensitivity to stress (Rimmer et al., 1994). These symptoms have been mainly associated with deﬁciencies in essential fatty acids (EFA) in particu- lar the long chain highly unsaturated fatty acids (HUFAs). Important HUFAs include docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (ARA). These HUFAs have critical roles in the development of the neural and visual system, structure and function of cell membrane and are linked to growth, survival and stress resistance in marine ﬁsh (Rajkumar, 2006; Tocher, 2010). The early larval rearing of barramundi in Australia in most instances relies on two microalgae for the rotifer feeding period: (1) N. oculata or (2) C. vulgaris. N. oculata has no or little amounts of DHA, but tends to be rich in EPA with some moderate amount of ARA (Lubzens et al., 1995; Chini Zittelli et al., 1999). On the other hand, DHA enriched C. vulgaris is low in EPA and has no ARA (Matsunari et al., 2013). The aim of this study was to test if the quality and performance of bar- ramundi larvae (growth, stress resistance and development) can be improved by feeding the larvae rotifers enriched with microalgae blends (C. vulgaris and N. oculata) in comparison to a monospeciﬁc diet.
Different species of fish may spend different stages of their life-history in freshwater, marine and estuarine ecosystems. In order to reproduce, anadromous species migrate from sea to fresh water, while catadromous fish spend most of their life in fresh water and migrate to sea. Diadromy may have evolved in fish as a means to take advantage of the favourable feeding conditions in the ocean (Gross et al., 1988; McDowall, 2008). Physiological changes associated with the diadromous habit have major influences on lipid metabolism, FA requirements and the resultant FA profile of the fish (Tocher, 2010). The rearing salinity of farmed fish affects their general physiology, osmotic regulation, lipid digestibility and, consequently, the biochemical and FA composition (Partridge and Jenkins, 2002; Haliloğlu et al., 2004; Jana et al., 2006). Lipase mediates lipid depletion in acclimation to salinity change, while thyroxine, cortisol, growth hormone and prolactin underlie alterations in lipid metabolism associated with salinity change (Sheridan, 1989; Jarvis and Ballantyne, 2003). Changing salinity had a significant effect on FA profile, mainly PUFA and the n-3:n-6 ratio, in fish. Early reports showed dramatic decreasing of the n-3:n-6 ratio of sweet smelt, Plecoglossus altivelis, when they migrated from freshwater to seawater (Ota and Takagi, 1977), while the ratio increased in masu salmon, Oncorhynchus masu, migrating from rivers to the sea (Ota, 1976). Barramundi can be ascribed to specific environments by examining their fatty acid profile where n-3:n-6 is higher in samples collected from saltwater compared with freshwater habitats, which is related to their natural diet (Bandaranayak et al., 2004). Other research found that diadromous or euryhaline fish have a higher n-3 LC-PUFA content and their ability to synthesize these FA from dietary precursors changes through the life cycle as in Atlantic salmon (Miller et al., 2008a). Salinity changes manipulated the n-3 LC-PUFA content in milkfish, Chanos chanos (Bautista et al., 1991; Borlongan and Benitez, 1992), rabbitfish (Li et al., 2008) and Japanese seabass (Xu et al., 2010).
The MSTN gene has been cloned and characterized in a large number of high value commercial fish species such as atlantic salmon , shi drum , rainbow trout , gilthead sea bream , white bass , Mozambique tilapia , catfish spp. [14-16], European seabass , striped bass , white perch , orange spotted grouper , Japanese sea perch  and croceine croaker . In fish, this gene consists of three exons and two introns. Exon 1, encoding for the N-terminal signal sequence for secretion, contains the highest inter-specific variability, while exons 2 and 3 are highly conserved across species and are translated into the pro-peptide and C-terminal bioactive dimer [15,21]. Alternative forms of MSTN have been independently isolated in zebrafish, gilt- head sea bream, fugu and salmonid spp. [9,11,22,23]. Different rates of identity shared between alternative MSTN isoforms suggests that at least two events of dupli- cation occurred in finfish. A first event, which separated MSTN-1 and MSTN-2, occurred early during teleost evolu- tion, while a second event, likely due to tetraploidization, occurred in salmonids (MSTN1a-2a; MSTN1b-2b) . According to Rodgers et al. (2007), the new nomenclature proposed for the MSTN gene family has been adopted in this study.
closely resembled that described in Asian seabass (Maneewongsa and Tattanon, 1982; Kungvankij et al., 1986), although develop- ment of the Australian strain of L. calcarifer appears to occur faster at similar temperature than that of Asian strains, particularly past the 8-cell stage. In our study, the Australian strain of L. calcarifer eggs incubated at 28 ◦ C hatched just under 16 h post-fertilization, com- pared to 18 and 17.5 h for the Asian strain of L. calcarifer incubated at 28-30 ◦ C and 27 ◦ C, respectively (Maneewongsa and Tattanon, 1982; Kungvankij et al., 1986). Interestingly, the Asian strain of L. calcarifer eggs incubated at 28–30 ◦ C (Kungvankij et al., 1986) developed slower past the ﬁrst cleavage compared to when incu- bated at 27 ◦ C (Maneewongsa and Tattanon, 1982). It is unclear why the eggs developed slower at higher temperature but this could have been inﬂuenced by multiple factors including ﬂuctu- ating temperature during egg incubation and gamete quality of the broodstock used for stripping (Palmer et al., 1993; Castranova et al., 2005; Stone et al., 2008).
cells that are capable of self-sustaining melatonin rhythms that will also continue in the absence of light stimuli (Bolliet et al., 2006; Migaud et al., 2006; Takemura et al., 2006; Falcon et al., 2007). A photoperiodic circadian system comprises of light entering fish and being transformed into a timed neural and hormonal signal (Falcon et al., 2010). Melatonin is one major output of the intra-pineal oscillators, which conveys rhythmic photoperiodic information to the organism. However, a number of species have evolved different circadian systems involved with photoperiod perception. In species such as European seabass (Dicentrarchus labrax) and Atlantic cod (Gadus morhus), full amplitude of melatonin production has been shown to rely on both the pineal gland and eyes to perceive photic information whereas in Nile tilapia and African catfish, melatonin production is solely reliant on the eyes (Bayarri et al., 2003; Migaud et al., 2007). Additionally, no endogenous circadian systems have been shown to exist in salmonids (Gern and Greenhouse, 1988; Migaud et al., 2006; Iigo et al., 2007). This demonstrates not all species react to photoperiod manipulation and artificial lighting in the same manner. In addition, for artificial lighting to be effective plasma melatonin levels are required to be reduced below a “critical” threshold level (Porter et al., 1999), thus melatonin analysis provides a valuable tool for assessing fish’s perception of light as well as the effectiveness of artificial lighting systems. As far as I am aware, this is the first study to ascertain melatonin synthesis in response to the light/dark cycle in barramundi, in addition to investigating melatonin synthesis in barramundi exposed to continuous light.
Studies on the application on other prebiotics in other fish species resulted in both increase and decreases on fat content in carcass. Many studies performed on prebiotics resulted in no significant changes for fat content in fish carcass. It was suggested that the supplementation of polysaccharides entrapped bile salts, reducing lipid solubilisation and hence preventing lipid accumulation (Sinha et al. 2014). However, the supplementation of 0.2% MOS in giant sturgeon (Huso huso) increased crude lipid carcass, which has been attributed to improved lipid utilisation (Mansour et al. 2011). This may have been the case resulting in the increased crude lipid content of the carcass. Nevertheless, as lipid content is a significant contributor to meat composition and quality, and therefore taste and texture, further studies should be conducted to investigate the effect of increased crude lipid content in Asian seabass carcass (Grigorakis 2007). Investigation into the composition of these lipids may also reveal potential accumulation of omega-3 long-chain polyunsaturated fatty acids, a desired trait from marine fish consumption in general.
We have generated a platform that allowed us to look at a moderate set of sex-related genes, which were carefully chosen based on earlier data from other species. Our study is the first to report such mid-throughput molecu- lar data regarding gonad maturation in the Asian sea- bass. The results in our study show that several genes that are known to be involved in reproductive functions are also conserved in their gene expression pattern in the Asian seabass. Our data also indicate that the process of gonad maturation has high individual variabil- ity and complexity. The expression patterns of our cus- tom gene set also reflected interesting aspects of the Asian seabass gonads and provided new insights into their sexual maturation and development. In the future, sequencing the complete transcriptome of the species and the use of a whole-transcriptome expression micro- array (or RNAseq), together with the working hypothesis that was developed using the zebrafish model, will help
Barramundi (Latescalcarifer) also known as Asian sea-bass is an increasingly important tropical aquaculture species of the Asia-Paci ﬁ c region and it is inevitable that breeding programmes for this species will soon commence (Macbeth et al., 2002; Wang et al., 2008). We are not aware of any published papers showing genetic gains for barramundi, and know of only one simulated breeding programme recently reported (Robinson et al., 2010). At the onset of any new breeding programme in aquaculture there is much to be gained by assessing wild genetic diversity as different strains may be more suitable for commercial production. The walk-back selection programme for growth rate proposed by Robinson et al. (2010) does not attempt to evaluate the potentially diverse strains from different geographic locations prior to breeding. In species other than barramundi regional sampling of strains has revealed a 52% difference between low and high growth in six strains of Labeo rohita (Reddy et al., 2002), a 73% difference in weight in ﬁ ve strains of Onorhynchus mykiss (Overturf et al., 2003) and a 104% difference in weight at 105 days between Abbassa and Maryout tilapia strains (Elghobashy, 2001). Differences within lines can also be large with
There are several advantages of using bivalve trochophores for larval fish feeds (Adly et al., 1994). In addition trochophores are simple to produce using sudden temperature and salinity shock. Trochophores are small in size, usually less than 60µ (Alagaraswamy, 1980). They have cilia and flagellates for locomotion. Live foods are able to swim in water column and are constantly available to fish and shellfish larvae are likely to stimulate larval feeding response (David, 2003). A common procedure during the culture of both larvae of fish and prawns is to add microalgae to intensive culture system together with the zooplankton has become a popular practice (Tamaru et al.1994). Live food organisms contain all the nutrients such as essential proteins, lipids, carbohydrates, vitamins, minerals, amino acids and fatty acids (New, 1998) and hence are known as “living capsules of nutrition”. Providing appropriate live food at proper time play a major role in achieving maximum growth and survival of the young ones of finfish and shellfish. For some marine fish species (groupers, siganids, snappers) very small zooplankton, such as trochophore larvae need to be used as a starter feed, since the commonly used rotifers are too big. Trochophore larvae of the Pacific oyster, Crassostrea gigas are 50 µm in size and free-swimming (slow circular swimming pattern) ciliated organisms which have a high nutritional value for marine fish larvae (Xing and Long, 1991; Harvey, 1996). Trochophore larvae may contain upto 15 % (of total fatty acid) of both EPA and DHA (FAO Corporate Document Repository). Veliger larvae (60-80 µm) can also be given as initial feed for fish larvae with particularly small mouths (Lim et al., 1982; Whyte, 1992; Marliave et al., 1994). The rate of feeding in post larvae (PL fed with trochophore of bivalves) of L. vannamei, P.monodon, M.rosenbergii and L. calcarifer ranged betwen 40.0% and 90.0%. The survival rate ranged between 40.0 and 85.0% in post larvae of L. vannamei,
Temperature treatments were selected based on a review of atmospheric and sea-surface temperatures obtained from Australian government databases (AIMS, 2012; BOM, 2012), and from a comprehensive review of river tempera- tures from previously published data (Pusey et al., 1998; Stuart and Berghuis, 2002; Webster et al., 2005). Based on this information, the two temperature treatments were as fol- lows: (i) a ‘typical’ temperature (26°C), which is representa- tive of the annual mean across the species distribution in Australia and the temperature at which the fish had been held long term; and (ii) a ‘warm’ temperature (36°C), which is regarded to be representative of the upper limit that wild populations experience (Russell and Garrett, 1983), but still within the known tolerance limits for the species (Bermudes et al., 2010). Prior to experiments, fish were removed from their holding tanks and acclimated to one of two tempera- tures in a separate system where water temperature could be closely controlled. While fish in the 26°C treatment group did not undergo a temperature change relative to prior holding conditions, fish used in the 36°C treatment group were accli- mated by increasing the temperature by 1°C per day and then
The segmentation cavity at the 16 cells stage was reported on the seabass Serranus atrarius (Wilson 1891). This configuration observed in D. labrax, and very prob- ably in many other teleosteans (as far as we know, not described), corresponds more precisely to the subgerminal cavity resulting of the enzymatic activity of blastomers leading to the lost of contact of the four central cells with the underlying periblast which represents an interphase between two different components: the yolk and the blas- toderm (Devillers 1961). The particular shape of the peri- blast of D. labrax embryo indicates the site of enzymatic reactions enabling the transformation of yolk reserves and the transfer of digestion products to the forming embryo (Kunz 1964).
investigated in this study is presently unidentified given the absence of diagnostic criteria to differentiate between geographical/host isolates and species (Whittington, 2004; Whittington, 2012). Phylogenetic analysis of approximately 12 Neobenedenia spp. isolates collected from multiple fish hosts in northern Australia is ongoing and may provide species level-clarification (Brazenor, unpublished data). Meanwhile, representative specimens mounted on slides were accessioned in the South Australian Museum, Australia (SAMA) in the Australian Helminth Collection (AHC); SAMA AHC 35461 (see Hutson et al., 2012). Parasite eggs were collected daily and held in Petri dishes with fresh sea water. Newly hatched oncomiracidia (<3 h old) were gently aspirated with a pipette and used in the experiments described below.