Effects of dietary supplementation with algal astaxanthin on growth,pigmentation,and antioxidant capacity of the blood parrot (Cichlasoma citrinellum × Cichlasoma synspilum )

An algal astaxanthin feeding trial was carried out to investigate the ef fects of natural astaxanthin from Haematococcus pluvialis as feed additives on growth, pigmenting efficacy and antioxidant capacity in blood parrot(C ichlasoma citrinellum × C ichlasoma. synspilum). Tissue total antioxidant capacity(TAC), superoxide dismutase(SOD), catalase(CAT) and maleic dialdehyde(MDA) were chosen as measures of its antioxidant capacity. All fish which received an astaxanthin(from micro-algal H. pluvialis) supplemented diet with 400 mg/kg of astaxanthin, after 50 days of feeding, the astaxanthin-fed fish displayed a pinkcolored skin and the control-fed fish displayed a grayish skin. For the growth, the weight gains of controlfed fish and astaxanthin-fed fish were 200% and 300%, respectively. Samples of skin and scales were used for analysis of total carotenoids and astaxanthin content, and fish feeding astaxanthin showed significantly( P <0.05) higher concentrations than the control group, indicating that the pigmentation of this fish had been significantly improved by dietary astaxanthin. Compared with the control fish, pigmented fish had lower SOD, CAT and MDA and higher TAC. It can be concluded that supplementation with dietary astaxanthin could eff ectively enhance growth, skin coloration and the antioxidant capacity of this fish. This study will provide a reference for application of natural astaxanthin from H. pluvialis as feed additives in blood parrot artificial breeding. Our data is also useful in ornamental fish farming, especially when the retentivity of astaxanthin in the skin and scales are involved. It is leading to the possibility of increasing the pigmentation of farmed-fish by adding the powdered form of H. pluvialis to the diet as an ef fective pigment.

ARTIFICIAL PROPAGATION AND BREEDING OF MARINE FISH IN CHINA

Since the 1990s, artificial propagation and breeding technique of marine fish in China have developed by way of increasing species and fry numbers, with special stress laid on valuable species. Large quantities of artificial fry can meet the needs of both marine cage culture and pond culture for most species. Experimental results obtained by scientists have been put into use in actual production. Fish fry production has entered a period of sustainable development. So far, at least 44 species (21 families) of marine fish have been successfully bred in China. The artificial fry number of large yellow croaker (Pseudosciaena crocea) exceeded 300 million in 1999. The species whose artificial fry numbers have each surpassed 10 million annually are red drum (Sciaenops ocellatus), Japanese seabass (Lateolabrax japonicus), cuneate drum (Nibea miichthioides), spring spawning red seabream (Pagrosomus major) and threebanded sweetlip (Plectorhynchus cinctus). Millions of artificial fry are bred annually in the species of black porgy (Sparus macrocephalus), Russell’s snapper (Lutjanus russelli), javelin grunt (Pomadasys hasta), miiuy croaker (Miichthys miiuy) and skewband grunt (Hapalogenys nitens). The fish in the family Sciaenidae are the main species in artificial propagation and breeding. Some problems and prospects on marine fish culture and stock enhancement are also discussed and some proposals for sustainable development are put forward in this article.

Identification of wild and farmed broadhead catfish (Clarias macrocephalus Günther,1864) based on morphometry,digestive indexes and flesh quality

Wild and farmed fish generally dif fer in their nutritional composition. In this study, adult wild and farmed broadhead catfish( Clarias macrocephalus Günther, 1864) were collected and were assessed for various characteristics, namely morphometrics, digestive indexes, and flesh quality. The morphometrics(standard length, body depth, eye width, fin height and tentacle length) and the digestive indexes(intestosomatic index, digestosomatic index, perivisceral fat index and activities of pepsin and lipase) diff ered significantly between the groups(P <0.05) and can be used to distinguish wild fish from farmed fish. In terms of protein synthesis capacity and color, the flesh quality was similar between the groups. However, radical scavenging activities and reducing power were significantly higher in the wild fish than in the farmraised group. The thermal transition characteristics of sarcoplasmic proteins, as well as myosin denaturation enthalpy and fatty acid profiles(C18:2 n6, C20:0, C22:1 n9, C24:0, Σpolyunsaturated fatty acids, and Σn–6) also exhibited potential to enable calls about the fish origin. The proximate chemical composition of whole body did not diff er between the two fish populations. Our findings suggest bioindicators, in terms of morphometrics, digestive indexes and flesh quality, that can be used to identify the origin of fish for forensic purposes, of for conservation biology of this near threatened species. The new nutritional information may be of interest to marketing, consumers, and has a connection to nutritional eff ects on human health.

Identification of Aquaculture-Derived Organic Matter in the Sediment Associated with Coastal Fish Farming by Stable Carbon and Nitrogen Isotopes

Abstract： Stable carbon and nitrogen isotope analysis was used to identify the aquaculture-derived organic matter in the sediment in and around a coastal fish farm in China. Results showed that mean δ13C value in fish farm area （within 1 O0 m from the edge of cages） and control area （500 m from the edge of cages） was -17.72±1.29/oo and -12.73± 0.380/00, respectively. Mean δ15N value of fish farm area and control area was 6.44 4±0.2%0 and 5.61 4±0.2%0, respectively. The sediment in the fish farm area was characterized by high waste food （47.70%） and faeces （27.71%） ratio, as the distance from the fish cages increased, aquaculture-derived organic matter decreased expontially （y = 97.167e-0.0074x, R2= 0.8481）. The spatial extent of waste dispersal extended to an area up to 400 m.